General guide to adjusting handling

[dnace]

Well since I always get the newb questions when at auto-x I figured I would post up some information.

The first is a section on how (in general) different settings effect a car. Auto-x'ers that play with tire pressure pay attention to the first two, as this is backwards from what most people told me the way to do it. Research says otherwise.

The second is a general area to start with tire pressure (source tirerack.com). Of course follow the tire specifications, but at least this gives you an idea of where to begin.

General pressure adjustments:
-When adjusting to change handling with tire pressure I find about 2-3psi adjustments to work best.
-I personally use the old school method of marking the tires with chalk or using polarized glasses. Some people prefer the more accurate method of using a pyrometer (which I will not get into) which helps you shoot to achieve settings with optimal tire temperatures across the tire. Since I cannot adjust anything except pressure at this point I chalk.

I will then adjust pressures down until I am maximizing tire roll-over. Typically there is a arrow on the side of the tire helping with this. Once you know general settings to get here, you can start the next race at these pressure settings and not have to get here again. I then adjust based on the course and how the car is handling.

I lower the pressure in the rear to incease oversteer and increase in the front to do the opposite. Of course you can play with just doing only the front or rear or both when making adjustments. Most people adjuct for optimum contact why still having the handling they desire.

This is only a general guide since so many people ask and I figured a reference might be nice. Post up if you have stuff to add or corrections!

*deleted chart since it SUCKS! boo tirerack!

[gary p]

The relationship between tire pressure and grip is not a direct, linear function. Assuming for a moment that other variables are fixed (spring/sway/shock rates, corner weight, alignement, ride height, suface friction, etc) for any given tire on a given corner of a given car, there is a pressure which that tire generates the most grip. Any adjusting UP OR DOWN from there reduces the grip. If your starting pressure is below the optimal grip pressure, lowering the pressure will lower the grip, raising the pressure will improve the grip. If your starting position is above the optimal grip pressure, the effects of lowering or raising pressure will be the opposite. If you are starting from a pressure of optimal grip, then adjusting up or down in pressure will reduce the grip. However, going to the higher side is generally more predicatble/stable than going to the low side. Thus the conventional wisdom of raising rear tire pressure to increase oversteer.

Given your method of starting at a pressure with "maximum roll-over," I'd guess you're starting on the low side of maximum grip. That would explain why your getting more oversteer by lowering rear tire pressure. If you're getting less understeer by raising rear tire pressure its because you are GAINING GRIP AT THE REAR, which would also imply that you'r starting pressures are too low.

Next time you need more oversteer try raisng the front pressure. If you can gain grip at the front and keep the same grip at the rear, you'll be faster than by giving up grip at the rear and keeping the same grip at the front.

[digitalseance]

This is good info for street tires...however R-Comps I've found to be a totally different game, but still the same sport (if that makes sense).

Using r-comps (hoosier A6s in my case), I've found what you're saying to be true to the point that you don't want to judge rollover as you'll basically never rollover too much until you're down to insanely low pressures. You treat pressures like a spring, if you want it stiffer in the rear, you increase the rear by 2-3psi and if you want it softer then you decrease pressures by 2-3psi in the rear. Same for the front.

[goodee]

If you have too much understeer apply more throttle in the corners. If you still have too much understeer you didn't apply enough of the aforementioned throttle and it's probably too late to try again. If you're too chicken to apply the appropriate amount of throttle slow the hell down next time.

If you have too much oversteer you should have used more brake on the straight part (the part just before you turned in with too much speed). In this case apply more throttle again and you will end up going in the correct direction eventually.

Oops, I should have prefaced this with the fact that these truths are most evident when driving a black Camaro. :D

[dnace]

The relationship between tire pressure and grip is not a direct, linear function. Assuming for a moment that other variables are fixed (spring/sway/shock rates, corner weight, alignement, ride height, suface friction, etc) for any given tire on a given corner of a given car, there is a pressure which that tire generates the most grip. Any adjusting UP OR DOWN from there reduces the grip. If your starting pressure is below the optimal grip pressure, lowering the pressure will lower the grip, raising the pressure will improve the grip. If your starting position is above the optimal grip pressure, the effects of lowering or raising pressure will be the opposite. If you are starting from a pressure of optimal grip, then adjusting up or down in pressure will reduce the grip. However, going to the higher side is generally more predicatble/stable than going to the low side. Thus the conventional wisdom of raising rear tire pressure to increase oversteer.

Given your method of starting at a pressure with "maximum roll-over," I'd guess you're starting on the low side of maximum grip. That would explain why your getting more oversteer by lowering rear tire pressure. If you're getting less understeer by raising rear tire pressure its because you are GAINING GRIP AT THE REAR, which would also imply that you'r starting pressures are too low.

Next time you need more oversteer try raisng the front pressure. If you can gain grip at the front and keep the same grip at the rear, you'll be faster than by giving up grip at the rear and keeping the same grip at the front.

You make some good points. I think we can all agreed on the apparent fact that it is not an exact science and you will never have the optimal pressure for each corner, as there are too many corners! I think you might be reading into my post or I suck at getting my meaning out. One thing I failed to add was I generally like to start a little ways above optimal pressure so it is like you say more predictable. and because I like to avoid using an air tank if I can. But I have for some reason over the past years, found the pressure quicker by coming up from under "optimal" using a tank. Call it luck call it too much inflation with the other method. However due to my lack of an airtank I have just been screwing with decreasing, and now recently having an air tank if I feel negative impact from a change.

You treat pressures like a spring.

haha it sounds like you are quoting, Pete he likes to use that analogy. :)



If you have too much understeer apply more throttle in the corners. If you still have too much understeer you didn't apply enough of the aforementioned throttle and it's probably too late to try again. If you're too chicken to apply the appropriate amount of throttle slow the hell down next time.

If you have too much oversteer you should have used more brake on the straight part (the part just before you turned in with too much speed). In this case apply more throttle again and you will end up going in the correct direction eventually.

Oops, I should have prefaced this with the fact that these truths are most evident when driving a black Camaro. :D

The whole time I was reading this I was thinking hmm sounds like you have drove the camaro too much.

[haunter]

You can't drive camaros too much


s2k's maybe

:p

[HBNR86]

The table that you put up with tire pressures is backwards to what i learned also. It is also backwards to what i have experienced. In my car if i want to decrease understeer I let air OUT of the rear tires. Seems to have always worked .....???

[gary p]

I think we can all agreed on the apparent fact that it is not an exact science and you will never have the optimal pressure for each corner, as there are too many corners! .


Another complicating factor is that the pressure which yields the most grip in steady-state sweeper may be different from the pressure which yields the best turn-in/transient-response.

[gary p]

The table that you put up with tire pressures is backwards to what i learned also. It is also backwards to what i have experienced. In my car if i want to decrease understeer I let air OUT of the rear tires. Seems to have always worked .....???

Look again. Chart says the same thing you're saying.

Decrease Understeer, Rear Tire Pressure, Lower.

[dnace]

The table that you put up with tire pressures is backwards to what i learned also. It is also backwards to what i have experienced. In my car if i want to decrease understeer I let air OUT of the rear tires. Seems to have always worked .....???

yeah that makes sense. Combining the chart with gary's clarification that makes sense.



Another complicating factor is that the pressure which yields the most grip in steady-state sweeper may be different from the pressure which yields the best turn-in/transient-response.

This is true any more I feel that when I think about it I am not necessarily adjusting for optimal grip but just the best handling that aligns with the way I drive the car. I would be curious to use a pyro to see how car off I am though, but I am afraid I would see my alignment is not optimal and get pissed off

[digitalseance]

I think going to the extreme of using a pyrometer on street tires is a waste unless you're running in ST (for autox).

So are we focusing on air pressures here, because we've yet to mention sway bars, shocks, or even springs...

[prostcj]

I've got a pyrometer if anyone needs to use it just hit me up at the next event.
I would say if you are brand new to a set of tires (other than Hoosiers) set tire pressure f/r to a cold pressure in the high 30's and chalk your tires. After your first run, see where the the chalk is worn to. If there is still chalk on the tread, lower pressure. If the chalk is worn off on some of the sidewall, raise pressure. Once you have that sorted out. If the car pushes, raise pressure in the rear. If the car is too loose, raise pressure in the front. This will let you adjust tire pressure without risking tire rollover.

[dnace]

I've got a pyrometer if anyone needs to use it just hit me up at the next event.
I would say if you are brand new to a set of tires (other than Hoosiers) set tire pressure f/r to a cold pressure in the high 30's and chalk your tires. After your first run, see where the the chalk is worn to. If there is still chalk on the tread, lower pressure. If the chalk is worn off on some of the sidewall, raise pressure. Once you have that sorted out. If the car pushes, raise pressure in the rear. If the car is too loose, raise pressure in the front. This will let you adjust tire pressure without risking tire rollover.

I might hit you up on the 20/21 I am just curious where I am at, I would be curious where I rank on the alignment and such too.


I have notice on the street tires I have been running it seems to get to a point where they won't roll and I still haven't hit the wear line. Why don't they raise that line? Is it possible I am still not using enough of the tire?

[prostcj]

Are you running a lot of camber? Could be the tread design wraps around the tire. Many street tires have heavily reinforced sidewalls so they might not rollover like a competition tire. I imagine S2ki has some threads that discuss tire pressures on the S. Good site, just don't like the street racing forum.

[digitalseance]

I would say if you are brand new to a set of tires (other than Hoosiers) set tire pressure f/r to a cold pressure in the high 30's and chalk your tires.
Interesting as Hoosier recomends a cold pressure of 26-28lbs...or is that the warm? darnit, I just threw the pamplet away yesterday! I always run 32psi in the front and start at 34 in the rear; but every car's different.

[StealsSouls]

Many street tires have heavily reinforced sidewalls so they might not rollover like a competition tire.

I was under the impression that race tires generally had much stiffer walls than a similar profile street tire.

[prostcj]

That's certainly not true of the A6's. The sidewall is made of cardboard I think. Can't complain though since they are very light as well.

[prostcj]

Interesting as Hoosier recomends a cold pressure of 26-28lbs...or is that the warm? darnit, I just threw the pamplet away yesterday! I always run 32psi in the front and start at 34 in the rear; but every car's different.

For the A6's? I read for a 3000 pound or more car you should run high 30's low 40's.

[Hornswoggler]

In my experience, and this goes against some of the resources I found on the net, is lowering my tire pressures gives me more grip on that end. For example, if I am oversteering, I usually drop the rears about 2 psi and that always seems to help. I start with cold pressures of 30 psi rear and 32 psi front, shooting for 40 hot on my Toyo RA-1's 235/40-17. When the pressures are higher, the tires feel "greasy" midway through the session.

With a track session time of 25-30 minutes, I am putting more heat into these tires than you guys probably see at auto-x.

If adding tire pressure adds grip, then why don't drag racers run very high pressures? If they are 20 psi rear, shouldn't they add another 25 psi to give maximum grip? I subscribe to the lower pressure = higher grip (wider contact patch) theory, but would love to see how these two camps compare.

I am well overdue for using a probe-type pyrometer for measuring tire temps and spread... I just error on the side of more camber! :)

[haunter]

In my experience, and this goes against some of the resources I found on the net, is lowering my tire pressures gives me more grip on that end. For example, if I am oversteering, I usually drop the rears about 2 psi and that always seems to help. I start with cold pressures of 30 psi rear and 32 psi front, shooting for 40 hot on my Toyo RA-1's 235/40-17. When the pressures are higher, the tires feel "greasy" midway through the session.

With a track session time of 25-30 minutes, I am putting more heat into these tires than you guys probably see at auto-x.

If adding tire pressure adds grip, then why don't drag racers run very high pressures? If they are 20 psi rear, shouldn't they add another 25 psi to give maximum grip? I subscribe to the lower pressure = higher grip (wider contact patch) theory, but would love to see how these two camps compare.

I am well overdue for using a probe-type pyrometer for measuring tire temps and spread... I just error on the side of more camber! :)

in my experience my hourish of track time at gingerman was easier on my tires than one autoX.....

and I think the low low PSI only rings true for straight line grip maybe?

[dnace]

Are you running a lot of camber? Could be the tread design wraps around the tire. Many street tires have heavily reinforced sidewalls so they might not rollover like a competition tire. I imagine S2ki has some threads that discuss tire pressures on the S. Good site, just don't like the street racing forum. Yeah I think you are right. This tire has one of the stiffest sidewalls I have driven, steering response is amazing, but still a street tire. I am running some pretty heavy camber numbers I will have to use the pyrometer to confirm these suspisions.

In my experience, and this goes against some of the resources I found on the net, is lowering my tire pressures gives me more grip on that end. For example, if I am oversteering, I usually drop the rears about 2 psi and that always seems to help. I start with cold pressures of 30 psi rear and 32 psi front, shooting for 40 hot on my Toyo RA-1's 235/40-17. When the pressures are higher, the tires feel "greasy" midway through the session.

With a track session time of 25-30 minutes, I am putting more heat into these tires than you guys probably see at auto-x.

If adding tire pressure adds grip, then why don't drag racers run very high pressures? If they are 20 psi rear, shouldn't they add another 25 psi to give maximum grip? I subscribe to the lower pressure = higher grip (wider contact patch) theory, but would love to see how these two camps compare.

I am well overdue for using a probe-type pyrometer for measuring tire temps and spread... I just error on the side of more camber! :)


This wouldn't necessarily be true. There becomes a point when you are too low and not optimally using the contact patch. I believe this is indicated by a lower heat in the center of the tire when using a pyrometer. I would say like I mentioned before if you start at a higher pressure and work your way down. Decreasing pressur will increase grip until you hit optimal then you lose grip. If we were to graph pressure versus grip it would be a bell curve with an optimal pressure. However optimal pressure I would argue depends on your driving style.


For those using a pyrometer here is the general guideline I run under:





Inside and outside measurements cooler, hot center = Tire pressure too high.
Inside and outside measurements hotter, cold center = Tire pressure too low.
Outside measure hottest, center hot, inside cooler = Needs negative camber adjustment.
Outside measure coolest, center hot, inside hotter = Needs positive camber adjustment.
Even temperature across inside, center, and outside = Perfect!

I forgot to add: take it RIGHT after running, without a cool down lap if on the track. (don't yell at me) and use a probe optimally.

[Hornswoggler]

I forgot to add: take it RIGHT after running, without a cool down lap if on the track. (don't yell at me) and use a probe optimally.

I nominate you as tire temp guy this weekend! :D

Edit: not to be confused with being the weekend optimal probe guy. :(

[dnace]

I nominate you as tire temp guy this weekend! :D

you have a pyro meter I would love to play. give me a notebook and the right tools and I will give you all the non-traqmate data you want.

[Hornswoggler]

you have a pyro meter I would love to play. give me a notebook and the right tools and I will give you all the non-traqmate data you want.

I'll find one. Berberich has one, I can either borrow that or if Bryan White has one at the track, should be able to use his. Counsil will be measuring temps on his Corsica too, so he might be bringing one.

[digitalseance]

That's certainly not true of the A6's. The sidewall is made of cardboard I think. Can't complain though since they are very light as well.
I'm of the opposite opinion. I forgot to check my pressures at the chicago divisional for my first run and had just slightly too much rollover with only 18psi in the front left! I think they're very strong. Any and every street tire I've autox'd on has had to have a minimum of 40psi to keep from rolling over on the sidewall. The STI/WRX stock RE92s run at least 48psi to keep from rolling over.

[prostcj]

http://www.hoosiertire.com/Tctips.htm#Tire%20Pressure%20Recommendations%20For %20Competition

[digitalseance]

I'll have to try that at the next event...

[Z3papa]

I bought into the "you need to bump your pressures up to 38 psi" when I started autocrossing and felt like I was on a lake in Wisconsin. By the time I figured out the process, I realized that it is so car specific. Weight of car, suspension, camber, type of tires, all affect which pressure is optimal for any given car. I now run my car at 33f/35r cold and dial down as pressures rise. Even then, my tires never/rarely show wear to the marks. I agree with Hornswoggler and DS, the lowest pressures short of rolling over onto the shoulder will give you the best grip/thread patch but take this with a grain of salt as I am not exactly burning up the results.

[prostcj]

This is why you use the chalk test.

[Kazz5]

Yeah I think you are right. This tire has one of the stiffest sidewalls I have driven, steering response is amazing, but still a street tire. I am running some pretty heavy camber numbers I will have to use the pyrometer to confirm these suspisions.




This wouldn't necessarily be true. There becomes a point when you are too low and not optimally using the contact patch. I believe this is indicated by a lower heat in the center of the tire when using a pyrometer. I would say like I mentioned before if you start at a higher pressure and work your way down. Decreasing pressur will increase grip until you hit optimal then you lose grip. If we were to graph pressure versus grip it would be a bell curve with an optimal pressure. However optimal pressure I would argue depends on your driving style.


For those using a pyrometer here is the general guideline I run under:





Inside and outside measurements cooler, hot center = Tire pressure too high.
Inside and outside measurements hotter, cold center = Tire pressure too low.
Outside measure hottest, center hot, inside cooler = Needs negative camber adjustment.
Outside measure coolest, center hot, inside hotter = Needs positive camber adjustment.
Even temperature across inside, center, and outside = Perfect!

I forgot to add: take it RIGHT after running, without a cool down lap if on the track. (don't yell at me) and use a probe optimally.

Agreed.

Without a pyrometer the changing of pressures can be a bit blind if not using chalk marks, etc. to gauge true rollover and, therefore, some impression of the actual contact patch being used.

[dnace]

even a pyrometer if not used right can give bad results. Optimally you want a probe and do it the second you stop. tires cool faaast

[350ZTRACK]

To clear up a few things. The reason they tell newbies to up their pressures, is because most people over drive their cars when they first start. After they realize what they are doing wrong, their driving, they will usually lower their pressures.
Another thing that makes a difference is tire construction. Most of your R rated tires, for auto-x, will have a fairly stiff sidewall to keep the tire from rolling over. Your road race tires will not have as stiff of a sidewall, because the turns on most road courses are not as tight as and auto-x.
You also have to consider the weight of the car. A heavier car will require more pressure.
Then there is also the driving style of the driver.
Last but not least is the suspension geometry. Some cars you can add a lot of camber, and you won't have to add as much pressure. Other cars you can't adjust the camper so they will take a more pressure.
The 2 biggest things that affect tire pressure are the surface, and the nut behind the wheel.

[msp857]

Even temperature across inside, center, and outside = Perfect!
.

Actually the perfect setup is for racing is to have the inside of the tire to be ~15degrees hotter than the outside.

[jstbrd]

I have a pyrometer and I think Marty has a probe...sounds like Dave is good to go!

[RacerX11]

I have a pyrometer and I think Marty has a probe...sounds like Dave is good to go!

I have access to a probe, but wasn't planning to mes with tire temps this weekend.

[Larz]

Too much psi causes only the center of the tire contact patch to contact. Less rubber on the road never equates to more grip. If that was the case vettes would come with wheels 7 inches wide.

[digitalseance]

The 2 biggest things that affect tire pressure are the surface, and the nut behind the wheel.
quoted for the truth :D

[dnace]

Actually the perfect setup is for racing is to have the inside of the tire to be ~15degrees hotter than the outside.

maax camber without too much tire wear is the goal right?

Most places I have read still say even temperatures for optimal grip

[Hornswoggler]

maax camber without too much tire wear is the goal right?

Most places I have read still say even temperatures for optimal grip

I have never seen any references suggest even temps, but the center should equal the average of inside + outside. I would expect a well setup car to have teh inside of the tire warmer (from the neg camber and long g's)

[gary p]

I have never seen any references suggest even temps, but the center should equal the average of inside + outside.


Yeah, 100 inside, 150 middle, 200 outside sounds perfect.... or not :disgust:

If your insides are hottest, you have too much negative camber.

[msp857]

If your insides are hottest, you have too much negative camber.
After talking to Dave Rosenblum (owner/driver/mechanic of Subaru Road Race Team), my friend Louis Gigliotti (Speed World Challenge Corvette) and my friend Mick Merrigan in Ireland (40+years driving/building forumla ford, touring car, rally of Ireland etc etc) over the past couple of years ALL of them have said the inside of a race tire should always be 15-20 deg hotter.

Googling "ideal autocross tire temps", the fourth link says:

Many people believe the proper tire temperatures a achieved when the temperatures are even across the tire. This is true if you are in a steady state corner all the time, but usually this is not the case. I normally want my inner temp to be 7-12 degrees hotter than the middle & outer temperatures. This is because of static negative camber & toe-out settings.

I do not measure my tire temps because I can only adjust my front toe-in, but is autocross a special case? Why would even tire temp be better here but not anywhere else?

Also, just pulled this from Hoosier's website:
Use of static infra-red pyrometers is an inaccurate method to monitor tire temps. Opinions? What do you guys use?

[marty]

Use of static infra-red pyrometers is an inaccurate method to monitor tire temps. Opinions? What do you guys use?

using a probe is what most prefer. the "core" temperature of the tire is a better representation of what is going on with the tire, due to dissipation of heat on the surface of the rubber (convection to the air, conduction to the road). there is a lot of heat generated by friction between the surface of the tire and the pavement, but there is also a significant amount of heat coming from the stretching and relaxing of the rubber inside the tread, down by the cords. a probe reading lets you see the effect of both heat sources since the interior of the tread is somewhat insulated.

[Z3papa]

Is it possible to have too much negative camber on a BMW? For cars having a neutral or oversteer issue, maybe but BMW's and many other cars for that matter have been developed intentionally to have minimal or substantial amounts of understeer based on the manufacturers belief that it is safer to have a push than to have the rear end of the car get tail happy. This is accentuated by a staggered tire setup which BMW is enamerated with. In autocross, that makes a car corner like a pig. So as a result, someone like Hornswoggler or I may resort to camber plates and other methods to gain a more neutral cornering aspect.

Disclaimer -- this rule does not apply to all cars but does apply to many.

[Hornswoggler]

Is it possible to have too much negative camber on a BMW? For cars having a neutral or oversteer issue, maybe but BMW's and many other cars for that matter have been developed intentionally to have minimal or substantial amounts of understeer based on the manufacturers belief that it is safer to have a push than to have the rear end of the car get tail happy. This is accentuated by a staggered tire setup which BMW is enamerated with. In autocross, that makes a car corner like a pig. So as a result, someone like Hornswoggler or I may resort to camber plates and other methods to gain a more neutral cornering aspect.

Disclaimer -- this rule does not apply to all cars but does apply to many.

As I understand it, our cars need more static camber due to the front strut suspension design... it is the nature of an independant suspension to decrease camber (be more negative) under compression or lowering, with other designs like A-arms being able to accelerate that camber decrease under compression, hence we need more static negative camber.

I want my alignment to help me be fast in the slowest parts of the course. I am not as concerned with the average, but rather addressing the bottleneck. Going fast and using consumables can be a tug of war. Even temps would help make for even tire wear, but maybe that most demending turn you are giving up grip in exchange for tire life?

[dnace]

After talking to Dave Rosenblum (owner/driver/mechanic of Subaru Road Race Team), my friend Louis Gigliotti (Speed World Challenge Corvette) and my friend Mick Merrigan in Ireland (40+years driving/building forumla ford, touring car, rally of Ireland etc etc) over the past couple of years ALL of them have said the inside of a race tire should always be 15-20 deg hotter.

Googling "ideal autocross tire temps", the fourth link says:

Many people believe the proper tire temperatures a achieved when the temperatures are even across the tire. This is true if you are in a steady state corner all the time, but usually this is not the case. I normally want my inner temp to be 7-12 degrees hotter than the middle & outer temperatures. This is because of static negative camber & toe-out settings.

I do not measure my tire temps because I can only adjust my front toe-in, but is autocross a special case? Why would even tire temp be better here but not anywhere else?

Also, just pulled this from Hoosier's website:
Use of static infra-red pyrometers is an inaccurate method to monitor tire temps. Opinions? What do you guys use?

See marty about the probe. IR isnot accurate enough because tires dissapate heat much too fast on the outside to get a fully accurate reading.

Auto-cross tire temperature you can still be beneficial. You may not be able to adjust everything at the track but you can still get an idea where you are currently at, hot your settting changes are effecting etc.

I do like the inside tire heat but agree it is not the average but the literal values. as 190-190-205 is more ideal. If I ever feel motivated I will go out and start verifying this stuff with data.

[gary p]

After talking to Dave Rosenblum (owner/driver/mechanic of Subaru Road Race Team), my friend Louis Gigliotti (Speed World Challenge Corvette) and my friend Mick Merrigan in Ireland (40+years driving/building forumla ford, touring car, rally of Ireland etc etc) over the past couple of years ALL of them have said the inside of a race tire should always be 15-20 deg hotter.


I do not measure my tire temps because I can only adjust my front toe-in, but is autocross a special case? Why would even tire temp be better here but not anywhere else?




Autocross is different from road racing because we are not bombing down straits at 120+ mph between turns, or braking from 120+ down to 60 , mostly in a strait line, setting up for a turns, for multiple laps in a row. With a bit of static negative camber that's gonna put some heat on the inside of the tires.

Relative to road racing, we are almost constantly loading the tires laterally.

[prostcj]

I can say that for autox, I'd be surprised if the outside of the tire was hotter than the inside by the time you measure core temps. Think about it. There is usually one tight, short turn before the finish and then you drive slow for about a minute and park. With any negative camber, the outside of the tire will be cooling faster than the inside at that point and will read a little lower.

[dnace]

I found out where I goriginally saw the even thing it was int "secrets of solo racing" by henry watts he mentions trying to change camber to lower heat to make it equal. shooting for the same temp but mentionns having the middle equal the average of the outside two

[Chefasaurus]

I don't play with tire pressures... I just mash the gas pedal and drive it until I hear the rim scraping... then mash the gas pedal HARDER! If it ain't broke, BREAK IT!





I kid, I kid....




FWIW... coming from uber-light, high-hp, low-tq, high-revving fully built, RWD racecars, to a heavy, mid-hp, mid-tq, mid-revving, FWD family sedan has been a WORLD of change for me. I got SOOO used to driving my RX-7's, that when I autoxed the Maxima for the first time, it felt like my first time autoxing all over again. I had to re-learn how to drive. Now, with the current state of tune that the car is in, it's a LOT more dialed in, as far as autoxing, but the deciding factor is tires. Torque steer, wheel hop, and understeer have all been cured by different bracing, swaybars, and bushings, but when 67% of the weight of the car is on the front wheels, you can imagine how inclined it is to understeer. Luckily, with the adjustability of coilovers, I've been able to dial in my "ideal" settings for autox.

Keep in mind, this is on 205/60-16 Goodyear Eagle LS 50K Mile tires.

Front: 47psi, coilovers set at half-stiff
Rear: 53psi, coilovers set at full-stiff

With all that said, it handles like a go-kart. Point and shoot. I'd really like to see what it will do with R-Comps before I sell it, but who knows if I'll get the chance!

[msp857]

Interesting... I guess it depends on what you are going for and how you are going about testing it. I emailed Hoosier for specific info because there is no info on their website, and here is the reply:

Ross,
Thanks for writing and for using our DOT competition tire, the A6. Because of negative camber settings for racing applications, you do want to see your inside shoulders between 10 - 20 degrees warmer than the outside. When cornering, you want the maximum contact patch on the ground, thus the -2 to -3 degrees of camber in the front end of your car. Usually FWD camber deficient vehicles(-1 degree or less), like the Mini-Cooper will have a warmer outside, thus wearing the outside more than inside. Now, a typical autocross may have fewer corners than straights, but when running the car straight with this much negative camber, you will see a warmer inside than outside. I would rather see more tread wear and higher temps in the inside rather than the outside(not enough negative camber).
I hope this helps and using a needle pyrometer after an autocross run will help find the maximum temps(use spray water to cool down before next run) and how the car / tire setup is being used.(adjust negative camber)
Hope some of these thoughts help.

- Jeff Speer, HRT

[gary p]

...when running the car straight with this much negative camber, you will see a warmer inside than outside....

- Jeff Spear, Hoosier Tire

He essentially affirms what I said. When you run on a race track with straits for a 20-30 minute race or lapping seesion you'll heat up the inside on the straits when you have enough negative camber. On a 55 second autocross run, however, virtually all the heat you put in the tires will be from working them in the turns. Thus the attempt to target ~even temps across the tread in autocross.

[gary p]

I can say that for autox, I'd be surprised if the outside of the tire was hotter than the inside by the time you measure core temps. Think about it. There is usually one tight, short turn before the finish and then you drive slow for about a minute and park. With any negative camber, the outside of the tire will be cooling faster than the inside at that point and will read a little lower.

I don't think that driving 600' from the finish line to the grid spot at 10 mph is gonna have a critical impact in the temperature differential from one section of the tire to another.

[msp857]

He essentially affirms what I said. When you run on a race track with straits for a 20-30 minute race or lapping seesion you'll heat up the inside on the straits when you have enough negative camber. On a 55 second autocross run, however, virtually all the heat you put in the tires will be from working them in the turns. Thus the attempt to target ~even temps across the tread in autocross.

:D Right, except he is talking about autocross and an autorcross tire - not track sessions. I agree that while in a corner you want your outside tires to be even temp, but what I am saying is that does not mean you should aim for even temps when you get back in grid. Also remember that the inside tire's contact patch during a corner is small, and on the inside of the tread. So the insides of the tires are being pushed on straights, and both when they are on the inside and outside of a corner, but the only time you are pushing the outside edges of the tire is when that tire is on the outside of a turn, and the contact patch becomes flat.

Even the sources that say the temp should be even also specify the center should be the average of the outer and inner - why? Well i'd imagine that means they expect them to be different when measuring, right? Anyways, I'll stop filling this beautiful thread by David with more debate and say: do whatever you want. haha

[dnace]

:D Right, except he is talking about autocross and an autorcross tire - not track sessions. I agree that while in a corner you want your outside tires to be even temp, but what I am saying is that does not mean you should aim for even temps when you get back in grid. Also remember that the inside tire's contact patch during a corner is small, and on the inside of the tread. So the insides of the tires are being pushed on straights, and both when they are on the inside and outside of a corner, but the only time you are pushing the outside edges of the tire is when that tire is on the outside of a turn, and the contact patch becomes flat.

Even the sources that say the temp should be even also specify the center should be the average of the outer and inner - why? Well i'd imagine that means they expect them to be different when measuring, right? Anyways, I'll stop filling this beautiful thread by David with more debate and say: do whatever you want. haha

This is all great debate! This site needs more of educational debate like this. That is partially why I started it! Gary I would think that even the 600' to the grid would be enough to lose outside tire temp. Now the question is would the internal tire temp loss be negligable when using a probe type. PS I am trying to secure a probe type for the next auto-x so we can try some of this stuff and post afterwards with our results.

[MoeBawlz]

Since this is a general guide, how about some newbie information (for newbies like me) For instance, I ran on my Azenis for most of this year at around 38/36 psi. The car drove fine as far as I knew, because I didn't know much better. I would push through corners and thought I was just at the limit of the tires and had to slow down a bit more in the corner or wag the tail around with a bit more throttle to get it to rotate. Well I just put on some Toyo T1-S and had them at 40/38 psi at the last WCMC event, and had that pushing sensation but WAY worse than ever before so at first I chalked it up to the tires not being as sticky as the Azenis. I figured id play with tire pressure a little and dropped my PSI down to 34/34 and it made a HUGE difference, the car rotated well and much less push and gained a whole lot of grip.

So my question I guess is on that table posted at the beginning it says if the car understeers to lower rear tire pressure or raise front tire pressure. Well it seems to me that the fronts were to high of pressure and couldnt grip the way they were suppose to. So is that guide really more of a tuning table as opposed to finding a ballpark initial pressure to work from?

Also is there any good resources to finding what PSI to run different tires at?

[digitalseance]

So my question I guess is on that table posted at the beginning it says if the car understeers to lower rear tire pressure or raise front tire pressure. Well it seems to me that the fronts were to high of pressure and couldnt grip the way they were suppose to. So is that guide really more of a tuning table as opposed to finding a ballpark initial pressure to work from?

Correct. If your pressures WAY too high, then you won't have the full contact patch b/c the tire is curved and scating vs flat and sliding.

Also is there any good resources to finding what PSI to run different tires at?
Consult the manufacturer, like what Ross did w/ Hoosier. When you buy a racing tire, they generally come with a pamphlet to tell you the recommended tire pressures. If they don't, then ask people who are using the same tire in the same vehicle who have been running them for awhile.

[marty]

moebawlz, read this. it was posted earlier in the thread.

The relationship between tire pressure and grip is not a direct, linear function. Assuming for a moment that other variables are fixed (spring/sway/shock rates, corner weight, alignement, ride height, suface friction, etc) for any given tire on a given corner of a given car, there is a pressure which that tire generates the most grip. Any adjusting UP OR DOWN from there reduces the grip. If your starting pressure is below the optimal grip pressure, lowering the pressure will lower the grip, raising the pressure will improve the grip. If your starting position is above the optimal grip pressure, the effects of lowering or raising pressure will be the opposite. If you are starting from a pressure of optimal grip, then adjusting up or down in pressure will reduce the grip. However, going to the higher side is generally more predicatble/stable than going to the low side. Thus the conventional wisdom of raising rear tire pressure to increase oversteer.

as for getting the 'best' pressures for your tires, it depends on a lot of things. the tire itself, the surface you're on, the car you're driving, and to a slightly lesser extent your driving style. best advice would be to find someone with the same (or similar in terms of weight, drive train, suspension...) car and same tires, then ask them what pressures they're running. of course, is there some guarantee that the pressures this person is running are 'right'? not really. but if they're beating you, then it might be worth a try.

[gary p]

:D Also remember that the inside tire's contact patch during a corner is small, and on the inside of the tread. So the insides of the tires are being pushed on straights, and both when they are on the inside and outside of a corner...

But most of the weight is transfered to the outside wheels and the outside tires are doing most of the work (and generating most of the heat).

It's almost a moot point anyway since few autocross cars can get enough camber get higher temps on the inside than the outsides. I still don't think you'd want to in most circumstances. Maybe if you have a high-hp RWD car you can generate enough friction on the insides under acceleration.


Right, except he is talking about autocross and an autorcross tire - not track sessions.

I question his understanding of autocross when he says something like this:
"Now, a typical autocross may have fewer corners than straights..."

[gary p]

Gary I would think that even the 600' to the grid would be enough to lose outside tire temp. Now the question is would the internal tire temp loss be negligable when using a probe type. PS I am trying to secure a probe type for the next auto-x so we can try some of this stuff and post afterwards with our results.


Yeah, there will likely be a litte temp loss in the 600', but it will be pretty uniform across the tread. Even at 3* of negative camber, there's not enough friction rolling that short a distance at that speed to heat the insides.

It would be easy to check going the opposite way. Starting with a car with a lot of negative camber and the tires at ambient temperature, drive it 600' at 10mph, then check to see how much heat the insides of the tires gained. My guess is almost nil.

[dnace]

Yeah, there will likely be a litte temp loss in the 600', but it will be pretty uniform across the tread. Even at 3* of negative camber, there's not enough friction rolling that short a distance at that speed to heat the insides.

It would be easy to check going the opposite way. Starting with a car with a lot of negative camber and the tires at ambient temperature, drive it 600' at 10mph, then check to see how much heat the insides of the tires gained. My guess is almost nil.

I think you would lose more temp coming off track than you could generate doing that. But like you said probably a moot point, being as it may be a few degrees. now on a track having a cool down lap instead of coming in would give you off readings. I guess in auto-x just come in and make tire temp the first thing to check.

So we have a lot of talk about tire pressures albiet because this is a huge grey area. How about suspension settings?

I can break off into another thread if needed what are people going for with their spring/shock setups? and how are you achieving/what are the results?

I remember Pete saying he like to set the fronts softer and the rears stiffer. To allow the car stability in braking (softer front weight is up there in braking) and allow easier throttle steer (weight to the back, stiffer responds more). It seemed to work well in the limited experience I had with it. Although he may want to clarify.

PS Gary is that you with the white miata and turbocharger, I can't seem to remember who you are.

[dnace]

Forgot to add my setup:

springs-shocks are stock:

Front: Camber: -1.5°, Toe: 0"

Rear: Camber: -2.1°, Toe: 1/4" in (total)

I am looking to dial out alot of the over stear tendency and to at the same time add camber for better performance without sacraficing too much streetability. I had considered front toe but chose not to in the end.

Currently running close to stock stagger on tires but will soon reduce that and up the sway bar stiffness to allow more tire with same handling

[digitalseance]

gary runs a blue STS2 miata


I use CUSCO Zero-2R Coilovers
Spring Rates: I'd tell ya but I'd have to kill ya :D Most likely higher than anyone here :)
Sways: CUSCO 22mm front, CUSCO adjustable 22mm rear
Endlinks: Poltec adjustable steel fronts, Poltec adjustable aluminum rears
Camber: -3.2* front, -.8* rear
Toe: 0 all around, but thinking of going a little toe in for next year depending on new wheel/tire feel

Previously have had a very neutral handling car with a tendency to oversteer slightly. With the new sand dune at Rantoul, the car oversteers waay to much. I'm switching to 18x10.5" wheels for next year with A6s all around so I don't want to change a whole lot (except stiffer springs) until I can dial in what I have with the new wheels/tires.

[gary p]

PS Gary is that you with the white miata and turbocharger, I can't seem to remember who you are.

I've been running my smurf-blue STS2 miata lately. Also have co-driven Dan Marx's black MINI Cooper and smuf-blue Renault LeCar frequently in the past several years.

[prostcj]

Yeah, there will likely be a litte temp loss in the 600', but it will be pretty uniform across the tread. Even at 3* of negative camber, there's not enough friction rolling that short a distance at that speed to heat the insides.

It would be easy to check going the opposite way. Starting with a car with a lot of negative camber and the tires at ambient temperature, drive it 600' at 10mph, then check to see how much heat the insides of the tires gained. My guess is almost nil.

Since I do have a pyrometer and have measured temps after autox runs let me tell you what I've seen.
I'm at negative 3.2 in the front and negative 1.8 in the rear.

The side of the car that was loaded for the last turn is about 5-10 degrees hotter than the other side. The insides are about 5 degrees warmer than the outsides. I'm not postulating here, I'm telling you what I've seen.

[gary p]

Since I do have a pyrometer and have measured temps after autox runs let me tell you what I've seen.
I'm at negative 3.2 in the front and negative 1.8 in the rear.

The side of the car that was loaded for the last turn is about 5-10 degrees hotter than the other side. The insides are about 5 degrees warmer than the outsides. I'm not postulating here, I'm telling you what I've seen.

The question at hand is whether rolling 600' from the finish to the grid at 10 mph with a lot of negative camber allows the outsides of the tires to cool more than the insides. I'm not sure how you're data relates? We don't know if the differential in temps across the tread were the same at the finish as they were in grid or not.

My experience and perspective also comes from a career of driving wheezing-slow normally aspirated four cylinder autocrossers. I suspect a high-powered car would put more heat on the insides under acceleration, especially if you have some wheel-slip.

[gary p]

Since I do have a pyrometer and have measured temps after autox runs let me tell you what I've seen.
I'm at negative 3.2 in the front and negative 1.8 in the rear.

The side of the car that was loaded for the last turn is about 5-10 degrees hotter than the other side. The insides are about 5 degrees warmer than the outsides. I'm not postulating here, I'm telling you what I've seen.

The question at hand is whether rolling 600' at 10 mph with a lot of negative camber allows the outsides of the tires to cool more than the insides. I'm not sure how you're data relates since we don't know what the temps were before you rolled to the grid.

[prostcj]

The fact that the last loaded side is noticeably warmer should say a lot since just 5 seconds earlier the other side was typically the one loaded. I think the point is r-compund tires change temp so fast that it is hard to get much useful data by the time you get to the pits.

[dnace]

The fact that the last loaded side is noticeably warmer should say a lot since just 5 seconds earlier the other side was typically the one loaded. I think the point is r-compund tires change temp so fast that it is hard to get much useful data by the time you get to the pits.

I think it would still be useful data. If your argument is true at least you could get an idea of over/underinflation. but maybe not as much camber data.

[gary p]

The fact that the last loaded side is noticeably warmer should say a lot since just 5 seconds earlier the other side was typically the one loaded. I think the point is r-compund tires change temp so fast that it is hard to get much useful data by the time you get to the pits.

Not saying that it wasn't the last turn that was the reason for the temp differential in your particular case. But for the sake of discussion there are other reasons that may cause one have higher temps in the tires on one side than the other after an autocross run:

- In an autocross there are always more turns in one direction than another. More chance for heat to go in one side than the other.

-The higher the slip angle, the more heat the tires picks up, especially the outside tires. If there is a particular turn on the course that you "drift" more than the rest that could influence the heat on one side over the other. Next time you come off the course after a spin feel the difference in heat on the tires that were on the outside of the spin as opposed to those on the inside. You don't need a pyrometer, you can feel it with your bare hand.

-Course elements NEAR the end, but not neccesarily the final element, may influence a tire tempurature differential. For example, the typical "big sweeper" at the far end of the Rantoul lot will put a lot of heat in the outside tire. When you run "clockwise" and that turn is followed by a high-speed slalom and then a quick right turn to the finish, the lefts tires are gonna be warmer not just from the last turn to the finish, but from the big sweeper earlier in.


While it would be nice to get tire temps the instant you crossed the line, the data you get when you get back to the grid is still useful. Its not like the tires quickly cool to ambient tempurature. The absolute temps may have come down some, but what you're looking for more than absolute temp is temp differential accross the tread. As long as you don't take too much time getting your three samples across any one tread the data is useful.

[dnace]

Ok I was looking at the chart from tire rack I posted it same toe-in on the rear should decrease understeer I went from 0-1/4 a HUUUGe difference and I notice more understeer. is this a reult of increasing the camber as well or is that wrong?

[MoeBawlz]

Just food for thought... You are mentioning taking temps at the end of the run, and somoene i believe Gary pointed out that temps will vary at different points in the track/course which is something you will never see with checking it after the fact.

but just as a crazy idea (probably not worth it unless you really want all the data possible) what about running 3 IR temp sensors across each of the tires and using some sort of storage device to record the data? Again this will probably be over the top to what many of us will ever need/use, but just a thought.

[prostcj]

They make real time monitors of tire temps and pressure but they only give temperatures at one spot and it would be tough to read in the middle of your run:p

[MoeBawlz]

im sure there is a way to record the data shown... hell you could even point a camera at the display if you really wanted to. And are you referring to it only records temps at one spot of the tire? or one part of the run?

[gary p]

Ok I was looking at the chart from tire rack I posted it same toe-in on the rear should decrease understeer I went from 0-1/4 a HUUUGe difference and I notice more understeer. is this a reult of increasing the camber as well or is that wrong?

I'm now convinced that chart is about worthless. I've never heard of increasing rear toe in doing anything but make the back less likely to rotate which would increase understeer. More toe in means the outisde rear tire has to generate a larger slip angle to acheive the same rate of vehicle yaw. Tires by their very nature resist slip angles.

[digitalseance]

but just as a crazy idea (probably not worth it unless you really want all the data possible) what about running 3 IR temp sensors across each of the tires and using some sort of storage device to record the data? Again this will probably be over the top to what many of us will ever need/use, but just a thought.
paging "segment analysis" :p :lol:

call trackmate, tell them we want temp readings too!!!111 :D j/k

I'm now convinced that chart is about worthless. I've never heard of increasing rear toe in doing anything but make the back less likely to rotate which would increase understeer. More toe in means the outisde rear tire has to generate a larger slip angle to acheive the same rate of vehicle yaw. Tires by their very nature resist slip angles.
Pete said he gave his rear wheels some toe out to increase rotation (aka induce oversteer) on his alltrack. I've been debating doing the same since AWD vehicles tend to be pigs and want to push. This season, I've had to use a totally different compound of tire to achive good rotation.

[prostcj]

I know in the EVO community, more toe out in the front helps turn in. I would think it should be the same for other cars.

[gary p]

Pete said he gave his rear wheels some toe out to increase rotation (aka induce oversteer) on his alltrack. I've been debating doing the same since AWD vehicles tend to be pigs and want to push. This season, I've had to use a totally different compound of tire to achive good rotation.

Are saying you're running different compounds front and rear to get rotation?



With a stock class FWD car, rear toe-out is one of the few things you can do to diminsh understeer.

[MoeBawlz]

so really there is no GENERAL guide in terms of alignments, due to the wide variety of changes between FWD, AWD, and RWD. So what are some GENERAL things we can comment on? Tire pressure seems to be general, but the wording in that chart is crappy and not accurate from what we have discussed.

What else is GENERAL information? Front and rear sway bar adjustments?

[MoeBawlz]

call trackmate, tell them we want temp readings too!!!111 :D j/k


Upon some quick research, the IR sensors are EXPENSIVE!!! $140 each for a basic model which would probably do what you need it to do, all the way up to $600 each. My thought was what about taking one of those hand held ones apart and looking into its inner workings and maybe making it work as an output device for continual readouts... again just a crazy idea.

[digitalseance]

Are saying you're running different compounds front and rear to get rotation?
Front: A6s
Rear: R6s

but all are 245/40/17s still, just different compounds. The R6s don't get up to sticky temps until the 4th run if things are going quickly and at the divisionals, they don't run that fast so they stay cold and provide less grip. Not exactly ideal, but if you can account for it and know the rear will slide, you can use the AWD and slide your way around turns....unless it's sandy rantoul. :D

[prostcj]

Mark Daddio ran 10" rims in the front and 9.5" rims in the rear of his SM winning EVO. The tires were the same size but I'm guessing the front ones had a larger contact patch. There are various ways to skin a cat. If you need to loosen the rear end you could do the following to the rear.
Increase tire pressure
Decrease camber
Increase rebound
Decrease tire and/or wheel size
Increase sway bar stiffness/size


I would think the best thing to do is adjust only one of these at a time. It all sounds easy enough but setting up the car right takes the kind of patience I've yet to find.

[dnace]

I'm now convinced that chart is about worthless. I've never heard of increasing rear toe in doing anything but make the back less likely to rotate which would increase understeer. More toe in means the outisde rear tire has to generate a larger slip angle to acheive the same rate of vehicle yaw. Tires by their very nature resist slip angles.

Yeah I took it out! that is the last time I quote tirerack!!

I do agree with the sway bar settings.

I stiffen/thicken my front and decreases oversteer. REar I soften and decreases oversteer.

Although here is more sites with that same chart with the same general chart.

http://www.kormanfastbmw.com/thandling.htm
http://member.rivernet.com.au/btaylor/BMWText/technical/SuspensionFineTuning.html

Tire manufactures:
http://www.bfgoodrichtires.com/bfgapp/popups/demos/demos_sportscar_1.jsp
and tirerack

at least from tire pressure. they all say increase = less oversteer on rear tires. Why are these sites saying that?!

that is four sites and two are reputable, what are your thoughts?

[gary p]

so really there is no GENERAL guide in terms of alignments, due to the wide variety of changes between FWD, AWD, and RWD. So what are some GENERAL things we can comment on? Tire pressure seems to be general, but the wording in that chart is crappy and not accurate from what we have discussed.

What else is GENERAL information? Front and rear sway bar adjustments?

-Toe out in front generally helps turn-in on about any car.

-More toe-out (or less toe-in) at the rear rear = more oversteer/less understeer,
-More toe-in (or less toe-out) at the rear generally = less oversteer/more understeer.

-Rear sway bar: bigger= more oversteer/less understeer, smaller (or remove all together) =less oversteer/more understeer.
-Front swaybar is more complicated. The general rule is bigger front sway bar = more understeer, but for many softly-sprung cars (i.e. most stock category cars) a bigger front sway bar can actually reduce understeer; especially those cars with strut front suspensions that have no camber gain on compression. Keeping the body from rolling over so much can keep the contact patches of the front tires closer to sqaure with the pavement which can increase front grip more than the weight-transfering action of the bar reduces front grip.
-Adjustable sway bars with multiple end-link holes....moving the end link farther out the lever arm (away from the bend) has the same effect as going "smaller," only to a lesser degree. Moving the end link in on the lever arm (closer to the bend) has the same effect as going "larger," except to a less degree.

-Increase rear spring rate = more oversteer/less understeer, decrease rear spring rate = less oversteer/more understeer.
-Increase front spring rate usually = more understeer, but see front sway bar for potential exception. Decrease front spring rate usually = more oversteer/less understeer.

-More rear shock rebound damping/less front shock rebound damping = more oversteer/less understeer in transition (corner entry/slalom/offset).
-More front shock rebound damping/less rear shock rebound damping = less oversteer/more understeer in transition (corner entry/slalom/offest).

[gary p]

Front: A6s
Rear: R6s

but all are 245/40/17s still, just different compounds. The R6s don't get up to sticky temps until the 4th run if things are going quickly and at the divisionals, they don't run that fast so they stay cold and provide less grip. Not exactly ideal, but if you can account for it and know the rear will slide, you can use the AWD and slide your way around turns....unless it's sandy rantoul. :D

Hmm, doesn't seem like it should be neccessary to have different compounds on a car/class that you have so much freedom to change suspension perameters. Instead of decreasing grip at the rear by running a harder compound tire to acheive balance I would be searching for solutions to increase grip at the front end. Less spring rate perhaps?



One idea for dealing with a car that handles well at some venues but understeers (or oversteers) at others:

When I had a very seriously prepared Neon ACR I had 3 reference marks on the rear control arm eccentric bolts; slight toe-in/slight toe-out/much toe-out. I could make quick on-site toe adjustments to suit the surface/course/weather conditions. Low ambient temps, low-grip surface, chance of rain, more slaloms than sweepers would be toe-in. Warm, dry day on high-grip concrete with lots of big sweepers would be much toe-out. Mixture of conditions/elements would be somewhere in the middle.

Now you may not need actual toe-out, but you may need varying degrees of toe-in. Or you may need a little to- out in some conditions and a lot in others. The challenge is to identify what works best at either extreme and establish the min and max limits.

[digitalseance]

I think you hit the nail right on the head with that on der....

The main reason why I ran those was b/c of $$. JBRacingTires are awesome except they deal with 99% road racing compounds. It took him 2 wks to find me some A6s and even then, he only found 2.

Next year will be the big determining factor. I'll put money down that you can find me at (non-disclosed location) testing before the beginning of next year's divisonals. Rantoul just won't cut it anymore with testing for GASS events. I need smooth concrete and asphalt.

To deter fender rub, I'll actually be going to even stiffer springs next year. Goal: less than .75" of body roll. If CUSCO can't help me there, it's either ZZYZX or custom Eibachs...

[marty]

are your springs 2.5"? summit has a nice selection, all the way up to 950 lb/in

[RacerX11]

If you plan to get serious about national-level events next year, used race tires aren't gonna cut it.

[digitalseance]

If you plan to get serious about national-level events next year, used race tires aren't gonna cut it.

I won't be:

I'm switching to 18x10.5" wheels for next year with A6s all around

but b/c of that, I might have to run two sets; one for local events (my current 17s w/ JB specials) and one for the divisional/natinoal events (the 18s).

[prostcj]

What's your plans for fender rolling/cutting? You plan on running 315's?

[Tingls2]

:yes2:Just for info: I always have a probe pyro and an IR combo unit in my trailer. It woud be available for use.

[dnace]

:yes2:Just for info: I always have a probe pyro and an IR combo unit in my trailer. It woud be available for use.

who is dis?

[msp857]

who is dis?

Is it Tom Ingles?!? The man himself? If it is, brandon (blue miata) wanted to grudge match you!!!

[digitalseance]

It is...tingles = Tom Ingles :)

[dnace]

Is that the black Vette. I know the name but can't remember the car

Please say hi to me next weekend I suck at names!

[RacerX11]

Tom Ingles drives a boosted white SM2 Miata.

[Hornswoggler]

Along these same lines, here is an online book:

Autocross to Win (http://farnorthracing.com/autocross_secrets.html)

[dgmiller]

Dave: I had to give up on chalking the tires when I went to race tires. The sidewalls are so stiff that they don't roll over unless you get way to low. When I had my Avons mounted last year they had to go to 65 psi to get the beads to seat. My street tires seated at 40 psi. The Hankooks were a little better, they seated at 55 psi but the sidewalls weren't 1/2 inch thick like the Avons were.

I use a pyrometer to check the temp. You are welcome to use it anytime. Watch the ads from Harbor Freight, they often have an IR one for $10.

I adjust the pressure down to get more traction. With the Hankooks I haven gone lower than 30 psi so I don't know where the lower limit is. With the Avons I ran them as low as 28 at times.

You've got rear wheel drive, if its understearing then give it more throttle to get it to come around, unless of course you haven't got any torque on hand.