Some wheels need shims for fitment reasons... Thes cars are a little limting as far as rim withs and tire size combos, because of the setup of the rear end...unless you add spacer shims or something. A 205 width tire should be okay, unless they're stretching on a 8' wide rim, then you might have some rub.
Of course, if they just say "you need shims" and don't explain what and why--They might be just charging you for a visit from Fong Shim- He's the asian guy who lives down the street.

 

I'd still bet dollars to donuts that it is something with the wheel/tire combo and not the suspension or alignment. There are so many little things that could cause the problems you mentioned. And the likelihood of these symptoms not showing up at lower speeds if it was a suspension or alignment issue isn't very good.

Just about any issue with your wheel and tire combo could be throwing it off. Uneven tread, tread wear, balance, bends, cheap tires, all of these things can contribute to high speed vibration.

 

i think its the tires my girl friend has the same problem on her jetta you can feel her car wobbling from side to side and she has the same brand tires to and rims

 

i think its the tires my girl friend has the same problem on her jetta you can feel her car wobbling from side to side and she has the same brand tires to and rims

 

These Kuhmos are suposed to be really good. . .
http://www.tirerack.com/tires/tires....odel=ECSTA+SPT

 

yea dude ... take it to the dealer ... thats your best bet. they'll know whats up.

 

I'd visually inspect the suspension components and check for any looseness in allt the parts.

If everything checks out ok, it's gotta be the alignment/tire balance. If you no longer have your stock steelies, try swapping the wheels F->R and R->F. If the vibration decreases, then it's gotta be the balance.

If not, then it's your alignment. I've gotten an alignment once, only to have my steering wheel off-center and have extreme vibrations at speed. The alignment was worse afterwards than it was before hand. I had to go back two times, and they couldn't get it right. . . so I tried another shop, and they fixed it on the first try. But this was on my last car, but still. Alignment/oil change techs can be pretty stupid.

 

I was having the same problem (shaking over 70mph) and got the tires balanced. Smooth as can be now.

 

Yet another possibility would be a brake caliper. I had an intermittant shaking problem with my Grand Am at 50-55 MPH. Took it to the dealership and cost me a bunch of money and 3 days for the guy to figure it out. One of the front brake calipers was sticking and he had to replace it. Works great now!

 

Be sure when you take it in to have them balance the wheels with stick on weights. With aftermarket wheels the old style edge weights arent the best.