Hello there and welcome to the BMW Car Club of America.

If you are a BMW CCA member, please log in and introduce yourself in our Member Introductions section.

Autocross tire pressure for Michelin Pilot Sports

Discussion in 'E46 M3 (2001-2006)' started by astappen, Mar 25, 2009.

    • Member

    astappen

    Post Count: 7
    Likes Received:0
    I've been Autocrossing my e46m3 which has stock 225/45-18 Front & 255/40-18 Michelin Pilot Sports. I've typically run about 40psi front and back but I've noticed more side wall buckling on the fronts then I would expect. The max pressure seems to be 50psi. What do you race with?
    • Member

    mattm

    Post Count: 211
    Likes Received:6
    You might be seeing a result of a lack of camber adjustment typical to the more current products put out by BMW. This applies to the stock vehicles, in as delivered condition. There are aftermarket products will allow you to get more negative camber and reduce the outer edge front tire wear.

    I have run high thirties on Hoosier A6s on my 330i with ZHP. Similar size wheels and maybe a tad lighter than your car.
    • Member

    astappen

    Post Count: 7
    Likes Received:0
    Thanks Mattm. I should have mentioned my m3 is a 2003. When you say "current products put out by BMW" what decade where you referring to?
    • Member

    mattm

    Post Count: 211
    Likes Received:6
    This decade and the past one. Starting with about the Z3 (mid-nineties), the camber adjustments typically allowed about 1° negative on the front. At the same time, most of the cars continued to get heavier and heavier.

    The 135i is the a great example of this. They are camber challenged and have a weight very close to its Three Series brethren. In an autocross environment, without changing from stock camber adjustments, the cars are very hard on tire wear. If BMW had permitted adjustment to 2° to 2.5° we could improve handling and reduce tire wear.

    Yes, aftermarket products can be used to address it, but for those that want to run in a stock set up, especially in SCCA, those products would not be legal.

    As an FWIW, I had a deposit for a E46 M3 in 2001. I even drove the "demo delivery" of a Laguna Blue one that all the dealers received for test drives. After seeing the weight (on scales and in print), I cancelled the order. The salesperson even called me when BMW said they could sell/release those demo cars to see if I wanted it. Nope. Just a pig with lipstick. :D

    I am theoretically on a list for a 135i Tii should they ever build them, but I am not holding my breath for now. :(
    • Member

    EuroWerkz1

    Post Count: 160
    Likes Received:1
    Althouh it is true that the E46 M3 is camber challenged and especially for anything as tight as an SCCA autocross there are MANY stock class E46 M3's that are extremely competitive in their classes. You can of course raise your front tire pressures, and lower the rears considerably and it will help but if you are getting serioius about this you should consider other options such as a different tire, or modifying your car within the rules, and most importantly talk to some club members that are autocrossing your car they will show you the way to success and fun. I can assure you E46 M3's can be both.
    • Member

    mattm

    Post Count: 211
    Likes Received:6
    Up in the New England Region of SCCA we use a deactivated Army Base/airport. "Tight" is not a word usually associated with that site. :) (Fort Devens in Ayer, MA)

    Boston-BMWCCA runs there, too. We have Mike Shields and Alex Shipkov running both club's event's on a regular basis.

    Pressures will only do so much as will tire sizes. Like I said, it would have been nice to have had the camber come "off the line."

    I never said the E46 M3 was not fun, just not competitive in a true autocross environment.

    Doug, are you coming out to the SCCA Nationals in Lincoln, Nebraska this September? The size and condition is supposedly autocross nirvana.
    • Member

    EuroWerkz1

    Post Count: 160
    Likes Received:1
    Matt is right, It would be great if BMW would build us another E30 M3, but that is no longer possible. However if you have an E46 M3 you would like to make handle better, contact me off board.

    AutoX nationals in Lincoln? Oh, that sounds fun!
    • Member

    mattm

    Post Count: 211
    Likes Received:6
    Doug, I have tried rummaging the official SCCA Forums and SCCAForums.com to find a link with some photos of the site but it is either too late or I am too thick to find a good one. On SCCA.com the Solo Nationals link is very dry looking without too much info. When I get a good link/site I'll post it to ya.
    • Member

    astappen

    Post Count: 7
    Likes Received:0
    Ouch :( Well I love my pig, even if it's covered in lipstick. :D
    • Member

    mattm

    Post Count: 211
    Likes Received:6
    Turst me, I would love to have one of those new pretty pigs with four doors and a V8. Who needs lipstick?

    As a disclaimer, we own '06 325xi (the wife's), an '05 330i w/ZHP, and a '96 318i.

Share This Page