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      09-20-2012, 01:19 AM   #13
BimmerRob08
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Drives: 2008 M3, Space Gray
Join Date: Mar 2008
Location: KIKR (ABQ), NM

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Quote:
Originally Posted by Eddy@ApexRaceParts View Post
I am currently out of the country so it will be hard to provide additional timely responses/posts to your question until I return, but I'm sure the other staff will provide a follow up via email to the question you submitted.

I'm sorry to hear you're having vibration issues with your wheels, I understand that can be frustration to trouble shoot, and determine the cause.

You mentioned light use for a year. Many variables can cause a wheel to be damaged from use. I'll explain below what may have happened here.

The traditional staggered combination we provide for the E9X M3 is 9.5" front and 10.5" rear. If this is the combination you have, then 245/265 is undersized for the wheel width (stretched). This is not the tire sizes we recommend to for this fitment, as we traditionally recommend 265/285 for those wheel sizes. We have customers who run narrower sizes on our wide wheels but we point out that it is not ideal, and that the tires will be stretched. This combination is usually done when reusing the tires from a previous set, and we point out that it is a short term compromise. Michelin PS2 tires are also known to run very narrow compared to other brands/sizes and they have a soft sidewall. The new Michelin Super sport (PS2 replacement) is noticeably meatier. Undersized tires provide less protection for the wheel rim, which increases the stress they go through. When a bump or pot-hole is hit, more stress is passed through to the wheel. Run-flat tires for example also stress wheels excessively, which is why it's common for brand new BMW wheels to crack on new unmodified cars (the 1 series is a good example of countless cracked wheels). It's very possible that an impact caused an issue here.

It's difficult to determine the cause of your issue as it's a recent occurrence that started after a spirited drive, and there is no way of determining what the wheels have really been through.

You describe wheel hop that can be detected by the technician on the balancer. Can you be more specific regarding the issue you're experiencing? Is the wheel lip bent, or is there another way you can define the characteristic of the movement?

Please provide as much detail as you can. Once we have a better understanding of the issue, we can determine if this is a warrantable issue, in which case we will provide replacements at no cost to you. If the wheels were vulnerable to extra stress due to undersized tires, it's very possible they were damaged from use that is not covered. If that is the case, we will still be able to provide discounted replacements.

I should be back in the office and available to follow-up on Wednesday. I apologize for having to provide a response that makes assumptions about your possible circumstances, but I wanted to provide a timely response.

Thank you for your understanding,

-Eddy P

Sir,

Thank you for the reply. Yes the tires size is from stock and was a short term fix since those tires were pretty much about 2 months old when I purchased the ARC-8's. The tires are slightly streatched but I don't consider them too far streatched. Compared to a stock ZCP M3 a friend has with OEM 19", the wall is pretty much about the same angled.

I am not running spacers with this set up. I mentioned spacers because I had to run spacers with the OEM 18" in order to clear the APracing calipers. So no spacers here as I know they were causing vibrations with the OEM 18" wheels.

The roads here in NM suck but because of that I am as carefull as one can be when driving around here. Most of the driving I do with this M3 is mainly highway use from Albuquerque to Santa Fe, 2 trips to Vegas, one to Colorado Springs and a few runs up to the crest which the road is pretty smooth for the most part. No real hard impacts that I would consider to be questionable as far as I remember.

When the wheels were brand new with the tires in question, it took the BMW dealer tech on a road force balancer 2 tries to get the front wheels zero'd out enough to where the ride was smooth from 0 up past 90mph and over. So again now after about 6,000 miles worth of driving, I developed the vibration again. I noticed last week on the way to the Crest as I was on I40East Bound that when I braked, the vibration was amplified and felt as a wobble in the steering wheel. Not the brake pedal. So that was when I decided to bring it to BMW for another balancing.

Now its certain that some tire wear will cause on a car like this to feel a out-of-balance situation at the wheels. But these PS2's have alot of tread life on them.

At the dealer, my rep there said the technition noticed a slight wobble on one of the rear wheels. I did not see it personnely but these guys are pretty good from my experiance dealing with them in the past. They did not think that all the wheels are out of run-out. I have the print out of the balance and just need to scan/upload it. But the right rear wheel required the most adjustment. The next day I had to bring it back to BMW because still I had an out of balance vibration in the steering wheel manifested at about 76mph.

It took him about 3.5 hours the next day to try to zero them out. The amplified vibration under braking is gone now but the steering wheel vibration is felt at about 80mph now.

To be clear, the vibration is very light and only noticable but not bad. But it should be smooth as it once was with OEM wheels and before I ever added APracing calipers.

I'm 99.99999% sure it's not the brakes. These brakes have never, ever even seen close to their max capability unfortunately and the brakes only have about 8,000 miles on them at the most and not tracked yet.

So its possible that the front tires are just slightly worn and cause this vibration but how is it possible that would mean every time I get new tires, after only 6K or more miles it'll vibrate and need to be changed? That's crazy I think. The last set of Michilen's I had where the OEM ones that came with the car brand new, lasted 25,000 miles when it was all OEM and never once did I feel a out of balance situation and at that time I lived in England where the roads suck almost as bad as here and I tracked the car at several different tracks including Nurburgring.

So I feel there are a few possibilites. 1.) the wheels are good and the tires are just slighly worn and the M3 is sensitive enough to feel the change. 2.) these wheel(s) took a hit and have a bend to one or more that can't be seen directly. 3.) The tech doesn't know how to balance wheels or the machine is out of calabration, which I seriously doubt.

Anyway, I'm trying to figure out how to go about this without having to get new tires just yet. BMW rep said there is a technition they have that is by appointment and he can fix slightly warped wheels. But I don't what any of the wheels to be damaged by that if that is possible.

Thanks for reading and hope you can give further advise.

RB
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