pozzi

iTrader: (4)

this is on the OBS...getting "cupping" on the outside tread blocks on the new wheel/tire setup (lowered it at the same time as installing the wheels & didn't get an alignment yet)
it's mostly in the rear and i notice a slight vibration that surges through the car at speed, mainly in straights. used to only be around 60-65mph (school zones) but now i notice it happen from 40mph up to about 70-80-ish...
but it's not a wheel out of balance feeling, since it seems to surge thru the car in pulses intermittantly...not a constant wobble feeling like a wheel out of balance and it doesn't increase in turns like a wheel bearing normally does.

i did all the work and tripple checked all the bolts by hand after hitting them w/ the impact upon reassembly. nothing loose or out of whack...super simple install really.

i have a couple theories:
#1: since no proffesional alignment yet, there is too much toe-in in the rear causing cupping & weird vibrations. (tires fighting each other on the straights)
#2: wheel out of balance or has something between wheel/rotor surface throwing it out. 9shouldn't have been, since i cleaned surfaces w/ wire brush and it didn't start until a few days later)
#3: wheel bearing?
#4: something loose causing things to slowly work loose unil catastrophic failure at high speeds (k...j/k)

i know what the common tire wear signs are and the causes, (inside wear, center wear, both outsides wear, etc....) but i can't remember if cupping can be caused by out of balance wheels or too much toe in in this case...

input.

sperry

iTrader: (1)

Cupping is usually from an out of balance wheel, bad bearings or some other such thing that causes the wheel to vibrate. A bad alignment won't usually cup the tires, that'll just cause the tires to wear unevenly.

How old is your car? It could be that the bushings are shot, allowing the suspension to vibrate. When you lowered the car, did you replace the shocks? If the shocks are mis-matched to the lower springs, or if they're old, they may not be damping the spring properly which can lead to vibration as well.

Batto

iTrader: (1)

Blown out struts can do that kind of tire wear as well. Do a jounce test

The vibration you're getting may be simply because of the uneven tire wear, plus tires don't stay balanced forever either. Excessive toe-in/out will cause a jagged wear from the inner tread - out or vice-versa, depending on toe in/out. Term for that is/was feathering. I call it stairs

If a wheel bearing is going out, lift the wheel in question off the ground, grab the top and bottom of the tire and try 'n move it. Any play, it's wasted. Watch for the rotor to move along with the play though. If it's not moving along with it, you've got something else movin 'round underneath. Another way to check is to take a sharp turn, shift the weight of the car onto that side in question. If it howls, look into a new bearing.

This is all just stuff I picked up from work. If anybody else out there finds this stuff to be wrong, please feel free to shoot me down, I'm not the best tech in my shop