sdg003c

I have a 1999 e55.

I had new rotors and brake pads installed by my mechanic. Since then between 45-50 MPH there is a vibration in the front of the car. Below 45 there is no vibration and above 50 the vibration goes away.

Do I need to get the front tires balanced?

Any help would be much appreciated

NAFT1

Short answer; probably so. Most large-chain shops' new tire installations include lifetime balance, so that would certainly be the first step if you have that available. The wide, low profile tires are much more sensitive to imbalance issues.

You should first consider, however, the age of the tires, milage, and wear pattern. Texas summers are famous for stressing the limits of tires' construction, especially if you have any kind of alignment problem, suspension play, or the tires are old enough that the rubber begins to deteriorate. It is also complicated by the fact that tires cannot be rotated because of the staggered fitment and directional tread of most high performance tires. The belts and plies can begin to come loose and will actually shift around inside the tire, and makes the tire impossible to balance for more than a few hours to days, if at all. For these reasons probably 1/4 to 1/3 of all of the tires on my E55 die this way when they appear to have 10-20% of the tread above the wear indicators left.

If you want to check yourself, our '99s have a full size spare that you can swap out a corner at a time to see if it changes or improves the vibration. There are a lot of rubber bits that I have been going through one corner at a time on mine.

PJmak

I think its obvious that its caused by new rotors and pads since it started happening after that.

NAFT1

I've never seen a rotor cause a vibration at certain speed; it is not inconceivable but there would have to be a serious casting defect inside one of the vanes to affect the balance at such a low speed. If it is a rotor causing vibrations, it is usually noticeable only when brakes are applied.

If it's related to the brake job, it would probably be that a wheel weight was knocked off/loose when the wheel was removed or reinstalled. The odds are that a wheel weight is missing or a tire has suffered damage in some way that is affecting the balance. Even a plug in the tread of a tire is often enough to throw off the balance, especially if it is closer to the sidewall.