My 98 BMW 740iL steering wheel vibrants between 52-58 mph. I put on new tires and the problem was less noticeable, but had gradually gotten worse. Any suggestions? Thanks

turn steering wheel hard back and forth while trying to turn key sounds like the steering lock tab causing problem

its your tires or balance. let me know how it works for u .

If you jack up 1 wheel off the ground and put the car in gear , you can watch the tire spin. You might see a bent rim. The shop that mounted the tires should have seen it and warned you though.

This most likely may be due to the new tires... make sure that they are balanced correctly... 1 out of 10 times this will happen and you should only be able to feel it at certain MPH... somtimes worse then others.

Well, assuming they actually checked all the bushings, ball joints and tie rod ends that only leaves the bearings/races and rack-n-pinion to check. You also need to check your motor and transmission mounts and bushings as well as the u-joints on the drive shaft if this is rear wheel drive.

I just had the same issue with a 1999 2500HD and the vibration got worse above 50 mph. Problem was resolved with a new driveshaft. Old one (aluminum) was badly out of true and the problem didn't really occur until I had the U joints changed - then bent driveshaft vibration was noticeable. New driveshaft resolved issue.

Do not use powersteering flued, use ATF. automatic transmission flued, in the above.

Hi:
Since your BMW 540 series is a rear wheel drive car, a common cause of that sort of vibration is often the U joints on your drive shaft. The vibration often only shows up and certain speeds.

It isn't a particularly expensive repair, but is something to have checked out!

caster,camber and, wheel bearings
have your car 4 wheel aligned this will adjust your rear caster and, camber.
have your wheel bearings checked

You may have rotated imbalanced wheels from the rear to the front .Its possible not to feel the imbalance from the rear as it is far less sensitive and not transmitting through the steering wheel. Check tire balance or move the tire back to their original position which might help veify the source of your imbalance.