New Tires/ Unsmooth Ride

[LGATL]

My car used to ride smooth as silk with my old Michelin MXV4 H-Rated tires (16'), but recently I had a flat that required me to go ahead and replace all the tires (had to replace one tire, but decided to do them all since I was at 32K miles on the set). Anyway, I saw good reviews about the Bridgestone Potenza REA960 Pole Positions, so decided to give them a try (went with Z rated this time). The car rides really well with these tires, but as you approach 60-70 MPH, a faint vibration comes in over the steering wheel and at times through the body of the car. Tires have been checked and balanced again by the tire shop (tire shop said tires fine, balanced perfectly, and rims fine), but I took it to the BMW dealer near my house for a "better" tire balance, and they said that I had two rims that were bent. Anyway, I had the lower control arm bushings replaced the other day by another BMW dealer (the one I usually use), and asked that they balance the tires again (no comments from my service advisor)....still have the faint vibration. Is it possible that I have more "feel" of the road by switching from H rated tires to Z, or could it be that one or two of my rims are in fact damaged? Just seems strange that this problem did not raise its head until I got the new tires.

[KeithS]

said that I had two rims that were bent.

That surely will do it. If you have bent rims, stop wasting your time and money on trying to fix it WITHOUT addressing the rims. You should see for yourself. Just have the wheels placed on a balance machine and spin it slowly while watching it (much slower than balancing speed). If it's bent, you will see it. BMW's are very sensitive, it does not take much to cause a vibration. Also remember 'most' rim bends occur on the INSIDE lip so look extra careful there.

[AF]

One other possiblity is out of round tires which can cause a vibration ... go to a shop that has the Hunter 9700 (your dealer might already have this machine)

One thing I can tell you is Bridgestones seem to transmit a lot more road feel through the steering wheel plus being that you went from the Michelin to the Bridgestones, I would bet that has a lot to do with it.

When I switch from my summer tires to all season, I always feel like the car is smoother and it all has to do with the tires.
You can try one thing if you want to try to figure it out and pinpoint it to one wheel ... use your spare and put it on one side then take the car for a spin, see if you still get that feel, then try it on the other side and see if you get it. this might help you pin down whether it is a problem with one of your new tires or if it is normal.
'
One other solution is try putting the front to the back and vica versa ...see if you ge tthe same feel ... chances of all 4 tires being out of round would be VERY slim.