Help, my steering wheel is vibrating from 50-80mph

[ADVANT123]

Ok, heres the scenario:

Recently had H&R Coilovers and Kuhmo Ecsta 712 supra tires (235/40/17 on my front rims only)installed on my 1997 M3. I had the coilovers installed before the Kuhmo tires and my steering wheel did NOT vibrate. Once I got the tires installed(I only had front tires installed, I replaced my rears with S03PP a few months ago), I noticed a slight vibration from my steering wheel. Initially I thought it might be added road feel since I upgraded the tire to a 235/40 instead of the usual 225/45 combined with the new installed coil-over system. So, I took the car to another reputable shop and had them re-balance the wheels. It turns out the slight vibration I was feeling before was the fact that the first shop didnt torque the lugs down properly and the wheels were ready to come off!

So, after the 2nd balancing and PROPER torquing of the wheels, for the first day or so I had little to no vibration. However, its been 2 weeks since than and the vibration(the steering wheels shakes harshly left and right and I can feel a vibration from the pedals and floor) has been increasing and has increased to the point where it scary to drive the car between the speeds of 50-80mph. I took off the front wheels yesterday to inspect them for bends and I checked all the suspension components to make sure everything was tight and connected(Everything looked OK). I used my torqe wrench to tighten the wheels down and today when I was driving on the parkway, it seemed like I made the problem even worse. This is the third time I have to get these wheels balanced. Is it that the shop is balaning the wheels wrong or is it that there is something wrong with the tires? I have a lot of wheel weights on the inside of the wheels, so I'm thinking they balanced the wheel correctly. Please note that the vibration is ONLY felt fro 50-80mph while going in a straight line. Any help is appreciated.

[GQ_Style]

Did you ever figure out your problem?

[FastForwardwhls]

There is a chance that because the shop didn't tighten your wheels down the first time you might have experienced some damage to the wheel. Sort of like hitting a 100 tiny pot holes everytime you drove the car......

-Eli

[Jim@tirerack]

http://www.tirerack.com/tires/tirete....jsp?techid=49

Take a look here. A vibration can be caused by a number of things. I would have the tires and wheels rebalanced just to be sure.