Car shakes between 55-75 mph

by Perry
(Fairfax, Virginia)

Pontiac Bonneville

I purchased four Goodyear tires with additional warranty for my Pontiac Bonneville from National Tire and Battery - NTB two years ago.

There has been an on-going shaking problem for 9-12 months; I have visited various NTB locations off-and-on and they have not been able to fix it, despite multiple rotation, balance and alignment.

The tire thread is very good and so is the appearance, although when my Pontiac dealer looked at them, they called them "dry-rotted". Moreover, my Pontiac dealer performed a Road-force test (for which they charged me $100) and they claim all four tires are severly out-of-spec/bad.

The dealer suggested wholesale replacement. NTB subsequently checked out the tires again and now claims it is not the tires causing the shake, but my wheels. According to NTB I have 1 severely bent wheel and two other mildly "bent" wheels.

I have 85,000 miles on my car but I take good care of my car and have never heard of bent wheels with no apparent cause. I can account for one when I went over a curb, but not three "bent" wheels.

NTB has refused to stand behind their warranty to fix my problem/replace the tires, until/unless I replace all "bent" wheels.

I had expected NTB to at least replace the two front tires--the most bent one they placed in the rear, but it has made no difference.

What is my recourse?

Editorial Comment: What a puzzle Perry presents.

If the wheels are suspect, but not confirmed as the cause, my inclination would be to try to confirm or reject them as being the problem.

Somehow, perhaps from an auto wrecker, or a car dealer, it might be possible to get 4 wheels, with tires from a car which has no problem. Borrow these and install on the car and do a test drive.

If there is a noticeable difference, then you know the problem is some combination of the wheels and the tires. If there is no difference there is some mechanical defect with the car.

Next, try mounting the old tires on the loaner wheels, ideally one at a time. If there is any difficulty in getting these tires balanced, you'd know the tires are defective, but if they are balanced without problem, and then result in a test drive without vibration you have proven that the problem lies in the wheels.

Of course all this experimenting will be time consuming and may cost enough that your simplest solution might be to simply buy replacement wheels to start, and you may have to replace at least some of the tires in the process.

Tires can be damaged because of mechanical defects in a vehicle (including faulty wheels).

Most manufacturers will guarantee their tires to be free of defects, but they can hardly be expected to replace a tire which becomes damaged because there is a defect in the vehicle.

TG

Car shakes between 55-75 mph

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