jw1977

I have 15,000 miles on my c2s, my front tires are original and I got new rears 3,000 miles ago. In the last few weeks i've been noticing a shimmy in the wheel while doing freeway speeds. It's bad enough my front passenger seat noticably vibrates when someone is not in it. Do I need to get my balance checked on my tires? I've never noticed this before, can tires just all of a sudden lose their balance? I did notice the front tires were slightly starting to cup but probably have another 10,000 miles left, could the cupping cause the shimmy?

cole328

Yes, tires can easily "throw a weight" on any car, not just a Porsche I'd have it checked out

rijowysock

either a thrown weight, or if raining its water in the wheels, or mud if you go 4 wheeling often.

p-cardriver

Cupping could cause it also, if it is bad. Had that on a BMW with Bridgestones and replaced with Goodyears - never happened again.

15k miles on original tires and you expect another 10k? That's pretty far to the right on the distribution...I'll bet the mean is around 10-12k.

boolala

I got 20K of wear from the rears and 40 K from the fronts. OEM Contis. They still had some decent tread left but I wanted to try the Michelins.

I have this same problem as the OP in my Benz. They told me the wheels are bent. That's yet another possibility if you hit a pothole or something.

kdurg

Yes, cupped tires can definitely cause vibration in the steering wheel. Particularly in that harmonic range of 60-70mph.

If they're cupped, even a road force balance measuring run out on a Hunter machine won't make a bit of difference. Either way, a balance is the first place to start.

Edgy01

What I do (especially when racing) is put duct tape over my wheel weights to make sure they can't be flung off.

MyEmily

So bring the to rebalance? It never dawned on me tire weights can be fling/flung off. I know it's glued on. Does it happened often?

cole328

Not that often, but it certainly can sometimes when the car is washed, pressure from a hose gets in there, glue gets weak, etc easy to look at your inside rims, and if you see a non-dirty spot, in the shape of a weight, then bingo.

jw1977

I took the car in and the front tires were not balanced. I still feel a slight shimmy and my seat still vibrates. It must be the cupping of the tires. Does anyone else's seat vibrate when doing freeway speeds?

Fahrer

Generally, vibration alt lower speeds ( 30-50mph) is from the front tires/wheels. Vibration at higher speed ( 70+mph) and felt in the seats is from the rear tires/wheels. Again, a generalization.

Rinty

I had a low speed (45 to about 65mph) tremble coming from my 993's front end. I had the tires balanced on a Road Force machine, but the problem persisted. The tires (Michelins) had about 4 mm of tread left.

I had new front tires (Sumitomos) installed and balanced, and that smoothed the car right out; it's just a pleasure to drive it again.

CarlJ

Even if you perfectly balance a tire on a dynamic balancer, you can still have an out of round condition from a slighty mishapen tire or a slightly bent wheel. It doesn't take that much of an out of round condition to produce a dramatic change in road force reactions at the high and low areas. You could have hit a pot hole and bent your wheel ever so slightly that it is visibly unnoticeable, but the oblong shape, even perfectly balanced when hanging in the air, produces a road force variation when you have surface contact when actually driving.

If you haven't, try using a shop that has a Hunter Road Force balancer. These balancers simulate road force driving conditions while it is balancing for a much greater reduction in vibrations, due to the simulation of actual road conditions. It can account for some imperfections in your wheels and tires that standard dynamic balancing cannot.

kauai_diver

Mine tends to vibrate but not the steering wheel. I got re-balanced and still has a slight shimmy. Turned out to be a slight bump within the wheel.

Our tires are so wide in the back the chances are high over time that you will run over a rock or something and cause an inward ding on the wheel. They compensated a little for that wheel but I can still feel a little vibration. It seems to go away after 20 mins of driving though.

camhabib

Brand new (2k miles) C4S and at around 75MPH, my wheel does some vibrations, left to right (steering column doesn't shake, wheel turns slightly and rapidly). You can feel something minor in the front seats, but it's mostly just the wheel vibrating. It's odd because it doesn't happen all the time or at the same speeds. Any suggestions?