2 different sets on same vehicle
 

Before you tell me it's a crazy idea...

I have the Toyo Proxes S/Ts (rears are 315/35/20) and even after road-force balancing all 4 tires, I've been having a vibration in the seats while over 65mph only. The dealer put it up on a lift and spun the tires and it looks like the left rear is pulsating from the side view, so it appears to be out-of-round. I'm assuming it's the tires and not the rims (replicas) in most cases that cause this visual anomoly? I got these tires a year ago and only got around to looking into this now.

The problem is these are discontinued in favor of the S/T II.

IF I can't get a replacement from anyone, would it be crazy to go to S/T II in the rears only and leave the S/T in the fronts (275/40/20)? The tread patterns are different but I'm not sure if much else is. I didn't ever plan on having these asymmetrical/unidirectional tires rotated anyway. The vibration is driving me insane.

First things, first: a PIA, but I would have that suspect wheel/tire combo
spun at low speed at a tire joint, and then spun with wheel only; that
will tell you whether it is wheel or tire.

If it is the tire, I would hunt the net for the same discontinued tire,
although any replacement will be new vs. the wear on the other side, rear.
Dunno how many miles the rears have...

If it is tire, and no luck with an identical replacement, the newer version
may be ok, or may ride a bit different. Hard to tell from the TR site pics
as to how diff the tread pattern is. But, if you are not paranoid, I think
the new rear set might be ok, but not ideal. My 50Cts.
GL,mD

well i had them spin the wheel/tire and they say it's definitely not perfect, but they also say the tire is not out of round (which means no manufacturer warranty). They also say they can't spin just the rim without the tire on the machine, but said it's a little off from what they can visually see. *shrug* Basically "nothing's going to be perfect" and "BMWs are very sensitive"... they spun the tire on the rim 180 degrees to match the high/low points - which is what I thought the other places had already done. This time the left rear took 2.5 ounces instead of 8 the road-force guy put on. Vibration still persists.

I don't know what to do anymore except to order another replica rim to see if that fixes it, but I won't because I'm also tired of throwing more money into this. I'd just like to know if it's possible if an out of round rim can cause a tire to warp enough for the vibration. I will go with OEM rims the next time if so.