Shimmy question re. new tires

[Mitch90535im]

General question -

Before new tires last week, silky smooth, zero shimmy.

After new tires last week, very noticible shimmy between 50-60 mph.

Can I be certain that it is the tires/balancing, or could the new tires have "enhanced" a shimmy with a different root cause?

I'm going to take it back to the tire store, but I know I'm going to hear, "It's the suspension, all BMW's are know for it."

[Mendozart]

What kind of tires did you get? They could be out of round. I would recheck the balance. Also, where did you go? Try to get them balaced on a Hunter machine.

[632 Regal]

does this shimmy go away after driving a while? Could be flat spotting which is pretty common when some tires are fresh, it goes away after time. Do you have stock rims or aftermarket? Hubcentric rings missing or something?

[Mitch90535im]

What kind of tires did you get? They could be out of round. I would recheck the balance. Also, where did you go? Try to get them balaced on a Hunter machine.

I bought some more Continential's because the last set were great. Bought them from a mom & pop shop where I've always bought and I'm going back, I just wanted some ammo to say, "hey it was fine before the new tires, so it can only be the tires."

[Mitch90535im]

does this shimmy go away after driving a while? Could be flat spotting which is pretty common when some tires are fresh, it goes away after time. Do you have stock rims or aftermarket? Hubcentric rings missing or something?

No rings. If it were new tire flat spots wouldn't it be noticible at any speed? This is shimmy only between 50-60. I haven't had a chance to do any freeway speed testing yet.

[Bellicose Right Winger]

Sounds like a bad balance. Did they put all the weights on the inside to keep the Contours looking good?

Paul Shovestul

No rings. If it were new tire flat spots wouldn't it be noticible at any speed? This is shimmy only between 50-60. I haven't had a chance to do any freeway speed testing yet.

[Mitch90535im]

Sounds like a bad balance. Did they put all the weights on the inside to keep the Contours looking good?

Paul Shovestul

Yes, inside only, and if I'm not mistaken, the last set of tires which were on the car when I bought it, had the glue-on weights on the wheels. I'm not sure what they used on this set. I'm going to make it a point to watch what they do with this re-balance. (if the guy ever calls me back)

[myles]

I had the same problem a couple of years ago with a new set of tyres. I was a bad balance. I took it back to them and they balanced it again with no change. So I took it to a recommended shop and they balanced it and I have never had a problem since.

[SRR2]

If it's not balance, which ought to be obvious as soon as you spin the wheel up on the balancing machine, and if it's not out of round which you can measure with a gauge as you turn the tire on the balancer, it could be irregularities in the way the belts lay under the tread, causing the tread not to track straight aroudn the periphery of the tire. It's not a common problem but I've run into it a few times over the years. Goodyear was the worst offender. Unfortunately these problems aren't easy to diagnose. The Hunter 9700 road force balancer is probably the best way to get to the bottom of the problem.

You sure your wheels are good and that the lug nuts were torqued properly?

[Kalevera]

I agree with what Steve said.

A trick I recently learned regarding messed up belts (not entirely because my shitty kumho ecsta supra 712s really need replacing/have multiple flat spots/out of roudness and are doing the same thing as described by Mitch):

When the car starts to vibrate, stop the car and do a(s close as possible to a) 90 degree turn, either direction, soft and easy. Start driving again and see if the shimmy goes away. Sometimes (as in, yesterday) mine are *holy ***** bad -- come off an expansion joint at ~ 60mph and the whole car deathwobbles. Sometimes they're tolerable. Man, I need new tires.


best, whit