on my 95 854T I've been getting a vibration as of lately at highway speeds and seems to be getting worse. I've been reading abit on the archives with no real difinitive luck. I've come across tires, caliper and drive axle.
Is there anyway of determining which it could be because I dont want to do them all. My tires are T rated...goodyear eagle GT II on 16" wheels. 1/2 life remaining on front. 90% on rear. I know the cheapest thing to try is balancing but could out of balance tires cause so much vibration at highway speeds.. Faster than 70 or 80mph it goes away. Under 55 the car seems to drive fine. Any input is greatly appreciated.

Thanks guys for inputs.

I ended up taking it in for balancing and to my dismay the one wheel had damage on the inside from impact. Probably due to one of the many millions of potholes this spring has produced. I must have hit one even though I try my best to avoid them.

The shop tried their best to balance it and rotated the wheels to the rear which it seems to drive a heck of alot better. I'm not noticing any wiggle or anything in the rear. Probably less weight on the wheel itself.
But I know its flawed and I'll have to find some source for a wheel. Hopefully from a wreckers or not.
Anybody in the Toronto Area know of a good place for a used or refurbed rim?
16" 95' 850T style??

You could do a visual inspection on the inside of the wheels to see if you lost a wheel weight on the rim. Just a thought. Good luck

as an experiment is actually to try switching the wheels/tires front to back. If it's tire balance, a bent rim, a broken belt or "flat spot" in a front wheel/tire you should notice a definite improvement. If not, it's something else.

-Punxsutawney Phil

that's usually unbalanced tires/wheels. if it's steering wheel, it's the front. if it's in the seat, it's the rear. also double check ur lug nuts. an out of round rim can also be the case, not if u r losing air pressure over a short period of time.

it is definitely in the steering wheel. I havent pulled off the front wheels since I've had the car. 1 year now. I've been trying the balancing route but most shops dont want to waste their time (it seems) on doing a simple job like that without an appointment. I did have the tires at their specified 44 PSI but I put that down to 32psi to reduce the vibration. (but not that much) only helped soften the ride over pebbles.

Mike, I would almost certainly bet that your vibration problem has to do with wheel balancing. I have a '96 850 Turbo with chrome-plated wheels and from time to time the balance will go off somewhat due to the "strips" shifting.
Because I have always bought my tires at Discount Tire (currently Kuhmo 712 Ecsta's) they are happy to do a high speed spin balance on their machine.
This has always solved my vibration problem.
A tech at Discount once told me that when you have wheel vibration that appears at certain speeds and then disappears, it was their experience that it was a wheel balancing issue at least 90% of the time. Good luck, Fred.