richardliebert

Problem: New 2005 CPO S500 4MATIC that pulls to the right. The wheel is also steering to the left about 10+ degrees in order to drive straight. Pulls enough that constant pressure is needed to keep going straight and car will exit from high-speed road (PA Turnpike) with no input from driver. Pulls to right even when on road crown that falls to left. Tuesday will be 4th shop visit. Wheel alignment was done by MB on proper rack and a castor bolt kit was installed. Now we're looking at tire replacment.

The dealer has offered to replace one tire free of charge. I think I need two tires, but that's just me.

Here is what I learned by using a tire guage on the tires:

[LF - 7/32 corner to corner] [RF - 7/32 on the inside, 6/32 on the outside]

[LR - 10/32 corner to corner] [RR - 7/32 on the inside, 5/32 on the outside]

NOTE: The tire diameter on both right tires decreases from inside to outside, and the RR tire has less diameter (worn) then the LR tire. I would think this would cause the car to pull noticeably to the right.

Any thoughts?

I'll post the "answer" later this week after we work on the tires.

tilolite

If the car is pulling only when accelerating, then your diff is the problem.

I would ditch the tires that are not wearing out evenly then redo 4 wheels alignment. General Exclaim UHP makes great, affordable (can't say cheap in this forum) tires that the M3 forum (which I frequent regularly) raves about.

I would ensure that all the tires properly inflated. I prefer 38 front and 40psi in rear.

Finally, there is something definitely wrong with your steering wheel needing to be 10degree off to be driving straight. Maybe the car had some front end collision that was never reported. You may have to lawyer up to get the dealer to do the right thing.

richardliebert

It was the tires. I put 2 new tires on the front and the best remaining 2 on the rear and it drives perfect. The dead giveaway was when I drove the car to the dealer in 20 degree air and it drove perfectly until the tires warmed up little, then it was horrible.

rccmerc

New tires corrected a +10 left steering wheel off center?

richardliebert

I can't explain it. The dealer did put the car on the alignment rack (again), so they may not be telling me something. All I know is it steers true now. The service rep at the dealer admitted he "knew" it was the tires all along. I guess he couldn't say anything because the sales department was still liable. OK, there is more to this story, but that's just political. I just wanted "you" to know what caused the problem so you could better evaluate your own problems if they ever occur moving forward. Alignment, then tires seems to be the mantra.

rccmerc

It is complicated when buying a Certifed Benz from the dealer. Evidently when you first buy the Benz and it is certified, if it requires work immediately, the used car department and salesman (via lost commission), are actually paying for the work. Then when the warranty "kicks in" it is being payed for by MB themselves. I think it usually is 30 days after the purchase of the vehicle that the warranty kicks in.

richardliebert

Thank you for your comments. You are correct. I was trapped between the sales and service departments, each of whom was trying not spend. They made me work way too hard for a resolution that was poor at best. At least it's behind me now.

I love that car!