nyc_qcar

I bought BBS rims and Michelin PS2s 255/35s. From the word go I noticed a resonance that was not there with the factory rims.

I got them rebalanced at a tire shop, although I *asked* for road force i later discovered they didn't do road force, just a regular rebalance. In fact I did this twice including a rotation for kicks. The vibration didn't go away. Perhaps if you believe in road force then this is to be expected.

The dealer was not interested in helping me, even with an alignment check, because they are custom rims.

I finally got them road force rebalanced for real at discount tire shop in florida, and this time I watched them do it tire by tire. One of the tires needed rotation on the rim. To cut a long story short (involving a roofing screw, a new tire, the second sidewall bubble since I got the tires, etc) I eventually left the shop with the machine satisfied saying the out of wack-ness on all 4 tires was within limits (eg, 13lbs, on one of them that I saw - whatever that means). I requested 40psi as I had been running with that for a while and felt it was more likely to protect the rims.

Driving long distance immediately after this visit the vibration and resonance was crazy. If anything, worse than before! It came on at 49mph, peaked at 53mph (with an associated steering wheel shake) then again peaked at 80mph (but no wheel shake) and went away at 90+. By varying my speed I could find exact speeds with resonance that would shake the car - cupholder, visors, dash, luggage, driver, etc..

I stopped at a station (with warm front tires) and measured air pressure.. over 48psi in the fronts, maybe 45psi in the rears due to the heat of the tires. I decided this may be contributory so lowered all 4 to 35psi. The resonance was MUCH reduced but there was still the tell-take shake in steering at the same 54ish speed. But overall it was now bearable at least. (35psi tires now have more sidewall flex on small sharp wheel motions though).

I've run out of ideas. The dsp9700 thinks the rim+tire combo is good WITH road force balancing. The car thinks not.. the set came from tire-rack with blue alloy insert rings that should make them hub centric.

I'm seriously considering giving up in disgust and re-sourcing factory alloys - if I can find 19" ones that'll take PS2s. But I'm also wondering if a pothole could have thrown out the front suspension somehow, that could otherwise cause this. Finding no dealer interested in helping me is making things much more of a pain. RS6 certified dealers are few and I'm not good at socially engineering them to do what I want. They just raise my blood pressure when they start to dodge responsibility. They also warned me a regular alignment shop can damage the alumnium components by using impact wrenches.

Finally, the car pulls to the right especially on slow braking from 20mph to 0mph, even on uncambered roads. It actually always did this from new so i'm thinking it isn't related.

help

jprice@CPS

are the wheels using the correctly sized hubcentric ring?

nyc_qcar

none of the half dozen who have put the tires back on the car noticed any slop before the bolts went in, but who knows.. i suppose even a tiny bit of play there could cause it.

CraigB

size should be stamped on them...should be 57.1mm

boostedfun

Greenwich is a certified dealer