longm1985

Ok, I understand there's tons of threads on this, but didn't find quite what I was looking for.

So. My car's had a vibration issue over 65 for quite a while. It's oscillating (comes and goes with a regular pattern), and I feel it in the wheel AND the rear. Like, the steering wheel will stop vibrating and still feel vibrating through the seat. The car has eaten through 3 sets of rear tires in 13,000 miles (like under the wear indicators), the fronts have never shown any wear. This has transcended 3 sets of tires (both front and rear) and two sets of wheels. Tires were Goodyear, Continental ExtremeContact Sport, and Sumitomo summer tires.

A few things to know: this is a 99, 18" aftermarket wheels now, 113k miles. NOTHING seems to be loose on any wheel; struts, tie rods, control arms, and bushings all seem fine. Passenger rear wears faster than the driver rear. I don't do burnouts or anything stupid.

Can this be just alignment related? Is there some part I'm missing here? Help, I'm so confused.

mistertate

Loose joints can lead to degradation of alignment specs. Small changes in toe can lead to big tire shoulder wear
You can’t really see play in the parts by prying, you have to take them off to witness the looseness.
113k is about when people start noticing the parts wearing out, depending on use.
I’ve been piecemealing mine with most of it replaced by 97k

ER17

I have a 997 with about 75k on it doing something similar. It's rhythmic, about a 2 second cycle at 75 mph. I'll check the suspension, but it seems tight. My Boxster has about the same mileage but no issues.

papasmurf

I had the same problem years ago with some older tires....was right around 65-70....faster and it might go away. I think the tires were old at the time as I have gone through several sets of tires front and rear since then without issue until a few weeks ago it came back. The car had been sitting about a month so my first suspicion was flat spots but it didn't get any better after 10m of driving. It turns out my tire pressures were a bit low particularly in the rear and setting them to factory specs fixed it all for me. My suspension apart from struts up front is all original with 120k miles.

longm1985

Let us know when you get that figured out. Maybe this thread will help someone looking for the same issue someday.

I'm doing a few things that need to be done hoping they'll help, like transmission mounts (front motor mount was done a few months ago and for some reason didn't think to do the trans mounts), re-packing amd rebuilding the passenger side CV (driver is newer), and while probably unrelated, front sway bar links too. Alignment after the skid plate goes back on, then tires. Hopefully something in this random assortment does something. If not, the hunt continues.