Last summer, I wrecked a Del Sol into a ditch and smashed the hell out of the front end; since then it's been sitting in a field. Finally the other day I decided to take the alloy wheels off and put them on a CRX I own, since it needed new tires and at the time of my wreck the Del Sol had brand new tires. All the wheels looked okay except for one which had been okay but gradually the tire had gone flat...so I took them to Firestone to get them all balanced and the one checked out, they said they were all okay and balanced, and got them put on. Now there's some shudder at any speed over 60 that seems to be emanating from the rear...could one of the wheels maybe be bent? Wouldnt they have been able to tell that when they tried to balance them? They all visually look okay, no obvious bends or anything, so did they maybe fuck up the balancing? It feels great below 60 but once I get up to speed it feels really unstable.

A bent wheel certainly is a possibility.

But it is also possible you've got flat spot in the tires from sitting too long in one place.

Try moving the tires around, looking to isolate one or 2 that might be the culprits.

Hope this helps.

i agree for the most part w/ capri but if it were a bent wheel it would proabably shudder like that even below 60. try rotating them and if that doenst help take it to have it aligned and balanced again.

Probably a balancing issue as I have experienced a similar problem several times, and it has always been solved with a fresh balancing.
Jake

ya the balance is off. it happend to my friend and his tire wouldnt stay still. :(

A bent rim will cause a shimmy over the full range of speeds, balance issues crop up at specific speeds. Check around and find a shop with a Hunter road-force balancer.

I once bent a rim in a pothole. Ended up causing vibration (felt in the steering) when installed in the front, but the problem went away when the wheel was installed in the back.

So who knows.....