Tire pressure for auto-x

[brodee]

what's a good pressure to run for an autocross? I have 225/45-16 Michelin Pilot Sports on my '89 325is.

[Sean]

It's always better to run higher up front and lower in rear.

High front pressures prevent folding over and low rear's help the tires grip better.

However, since you have 225's 16in tires all around, I'd say maybe 36-38 psi up front and 34-36 psi in rear - don't forget to set these before your first run, and check them after each run - the tires DO heat up, which in turn raises pressure.

I'm not sure what those tires are like, but on my street tires, I had rear pressures around 33-34 - and it helped grip around the corners a lot better. Course, I was running on 195/65-14 Toyo Spectrum's all teh way around...

[brodee]

Thanks, I appreciate the help. Saturday is my first auto-x so it should be an experience. I did run a DE track event in my e36 M3 but this should be a lot different.

[Sean]

No problem, you'll REALLY enjoy it. It's tons of fun. Best thing to remember is to shift when the time comes. PLEASE don't bounce off your rev-limiter. I cringe when I'm working a course and I hear people bouncing off their limiter.

Not only is it not good for the engine, when you let off the gas, it only slows you down even more.

Also, walk the course more than once, try to find the apex for each corner, and try to decide what speed you may be going at some point, and figure out if you can take a corner wider - which lets you carry more speed.

If there are any slaloms, pace between the cones - this helps you decipher (sp?) if the cones get closer together or not. The significance of this is that if the cones get closer toegther, you won't be able to keep the car on the ground if you are accelerating a little bit in this slalom - since it gets tighter towards the end.

I can't think of anything else there right now. I'd suggest some asking some experienced people to ride with you once or twice, and let them know if they have any suggestions. It's always great to have someone suggesting what to do - since its your first time and all.

Oh, another thing, think about the way your steering too. DO NOT put your hand under the steering wheel, I hate seeing people drive that way on the street, much less at an autocross (when you put your hand inside the wheel at the top - upside down). I'd suggest shuffle steering or hand over hand - I've been trying to use both. Also, when not making a major turn, try to keep both hands on teh wheel at 3 and 9.


here's a thread for ya: http://www.r3vlimited.com/phpBB2/vie...hlight=shuffle

And a page about shuffle steering: http://koniaris.com/auto/steering/

Have fun!! :twisted: let us know how you do. ;)

[greateratlanta]

Here are some useful links that will give you general info, like what to expect, what to bring, how to walk the course effectively et cetera.

http://www.tunnellracing.com/advice.html

http://www.tirerack.com/features/solo2/handbook.htm

[LowR3V'in]

DO NOT put your hand under the steering wheel, I hate seeing people drive that way on the street

lol. Why?
I drive like that all the time btw. Allot better then driving like a granny 10-2


brodee I Don't know what tire pressure works for you, but
basicly want less in the rears :o

I have 205/70/14 back and 205/60 front and 23 in the back and 34 at the fronts werk
best for me.

[boom-monkey]

I like to run my tires at a lot higher pressure than on the street. During the last 3 autocrosses I've been toying with the pressures and have come to like 42 front 40 rear. It's really more of a personal thing though, as only you can tell what your car is doing. Also the type of tire has a lot to do with it as well.

[318daily]

I run something like 36 PSI front and 34 PSI rear. Pump them up high in the morning and you can always release air as the day goes on. Your pressures will naturally increase as the tires heat up.

Lift your head and don't concentrate too much on the turn directly in front of you, instead concentrate on the next two turns in front of you.

Also, brake while you are in a straight line and gun it through the turns.

I am a fan of bouncing off the rev limiter, as are the people that usually get the top spots.

[Mystikal]

Even with my super stiff Azenis Sports, I ran 40psi in my fronts and it felt quite good. Probably bump it up to 42 for the next events. I had the rears at my street-level 35psi, and that felt fine, plenty of treadpatch on the ground for acceleration.

[Crazyboy325is]

I have been running 39f/35r with my Azenis's in 14". You just have to play around until you get the handling you want. You can chalk your sidewalls for aditional info as to whether the sidewall in bending over due to lack of air.

Also, ride with as many experienced drivers as possible, and have some ride with you.