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Should I change my tires or just the front axle geometry

Discussion in 'E46 M3 (2001-2006)' started by loliea, Oct 11, 2008.

    loliea guest

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    I am kindly requesting the help of some expert :confused:

    I did couple of track days and I noticed that the outer shoulder of my tires looks pretty worn-out (see pictures bellow). Is it because of the design of these tires (PS2) or is it because the front axle geo is not good?
    As I am going to Infineon next month (with BMW Golden Gate Club) I am wondering what I should do?

    This is what I have:
    68k miles
    Michelin PS2 OEM size
    19 inch OEM wheels (not CZP)
    Stock suspension (RTA and RUSM changed 10k miles ago but otherwise stock)

    Front Axle geo (within manufacturer range):
    Camber L: -1.09
    Camber R: -1.07
    Toe L: 0.09
    Toe R: 0.09
    Caster L: 7.13
    Caster R: 7.00

    Note: this is my everyday ride so nothing too extreme for the setup

    Thanks for your suggestions :D

    • Member


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    Where to start? First of all everything is normal for the car, for the tires, and most importantly for the driver. You are using the outsides of your tires because the car is under steering in the corners, on top of that you are likely further punishing the tires by asking them to turn well after they have lost traction to do so. This is a very common mistake and nothing to be concerned about. Unfortunately the PS2 cannot be switched on the wheels to compensate for this wear since it is directional and must be mounted with the large tread blocks outside. In short it is time to relax the steering in the corners and try to make an effort to conserve the front tires and smooth out your driving style. Yes, you could modify the car to make this less of an issue but that will defeat the purpose of learning how to properly drive the car. Get with an instructor who is experienced with the same car you are driving and he/she will show you weight transfer and driving techniques to help alleviate these issues and to further your high performance driving education. It's all part of the process. And by the look of those tires , your having plenty of fun!

    Carry on!

    loliea guest

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    Yep, I had a GREAT time, even if I was exhausted at the end of the day...:D

    Smooth and mass transfer, that sounds good!
    Thanks for the wise reply:cool:


    dmd5 guest

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    You may be doing the same thing I did before I realized my mistake. More and more power in turns to try to go faster. In reality, I was fighting the front end, creating more "push" or understeer instead of easing OFF the throttle. Ease off the throttle to unweight the rear end, the rear will rotate around to aide turning. Gradually reapply throttle to straighten it out as you sufficiently tighten the arc of the turn. When I realized how to do it, I appreciated the brilliance of how BMW's handle so well..even I can do it! Have fun! Also, Skip Barber "Going Faster" book and video changed my life.
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    Brian A

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    There is a video???!!!? (I love that book.)
    • Member


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    Popping in to say I'm delighted to see these answers. In too many 'Car Guy©' forums, the replies will be directly to your two posed alternatives (change tires; change suspension geometry) without consideration of the real issue, which may be change the driver.

    One thing you overlooked is showing us your rear tires. If you are wearing them about the same as the front ones (OK, a little less), you're doing just fine. Yes, the outside shoulders will wear a lot when on track but, hey, you don't use that part on the street anyway! :D

    Your in-car instructor should be able to help you develop a feel for whether the car is doing all it can and whether you're in control or slightly beyond it. A simple look at the front tires (only) doesn't tell us nearly enough. Heck, maybe they were just underinflated. We can't tell without knowing the numbers.

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