I just added some new wheels this past week, rpm 505's with 225/40/18 tires. They look great and ride just fine, but on the freeway i noticed an odd and very unnerving problem. Above 43 i would say up to 65 (fastest i took it with the problem) there feels to be a failry strong shimmy in the front end. I had a small shimmy before (thrust arm probably) but it went away after like 55mph and wasnt more than annoying. This feels strong and im affraid i may break something driving like this? any ideas?

re-torque bolts.

A slight out of balance condition or out of round condition could make the slight shimmy you had before worse, which is what might be happening. Since you had a previous isse, a through suspension inspection, indicated repairs, and a true BMW four wheel lignment (including weighting the car seems indicated. When that's done you can address any problems with the new wheels/tires.

When I went to my Contour reps it made all my shimmys worse. I went to a larger wheel, and a heavier replica, I would guess that the increase in unsprung weight is the source of the problem. If you're sure that the wheels are true and balanced properly (Hunter Road Force), then why not fix the worn out suspension? I did my rear dogbones, rear sway bar links, and Racing King subframe bushing inserts last weekend and it already drives like a different car, can't wait until I do the front later this month.

i havent changed the suspension stuff yet because of the cost and the time. I need to drive a couple hours on the freeway in a few days and im nervous doin so in the car right now. I mean doenst doin the whole front suspension like that cost about $700

dude u need to rebalance ure tires. .... they didnt do it right

You don't always have to do it all. Here's a great reply from bimmer.info.

There area number of fast and dirty methods of checking suspension components, most require an asistant.
On a flat surface, have an assistant idle the car backwards and lightly load the break until almost stoped, then shift into drive just before the car comes to a complete halt, be sure to stop breaking before you go into drive. This will "load" every thing forward. Now walk along side the car as it idles forward, have your assistant abrubtly jam the brake on and off. If the thrust arm bushings are bad, you will see the wheel move straight back several inches and hear a clunk sound.

Keep in mind that when thrust arm bushings fails, it is not linear motion that causes the clunk. The rubber connecting the outer portion of the bushing rips away from the inner portion and allows the arm to shift lateraly and it bangs against the chasis. This lateral motion effectively shortens the moment arm and allows the wheel to move back pivoting arround the lower control arm causing pull. spring pressure then forces the bushing to "re-align" eliminating the pull, so we feel a shimmy. visualy inspecting the bushing in car usualy won't yeild good results unless it is comepletely raged out. You can sometimes attempt to pry the arm side to side and see if it will move, about 1/8"-1/4" is normal stretch for a used bushing. also look for marking on the chassis showing where the thrust arm has made contact.

As for checking other suspension components, I prefer to do the initial test with the vehicle flat on the ground when feasable. Start by well jouncing the vehicle(driving it it best), with the engine running have an assistant move the steering wheel back and forth while you reach under the car and grip each joint one by one. It is important that the steering wheel be moved properly, both for safety and good diagnosis, You may have to do test with engine off, if your assistant has trouble feeling the slop area with the engine running. move steering wheel slowly to just a smidge past the slop area back and forth. Move the steering wheel abrubtly back and forth a smidge past the slop area. Move steering wheel slowly but firmly about 1-2" past the slop area. Move steering wheel abrublty and firmly about 1-2" past the slop area.
Some joints will be difficult to safely wrap your hand arround, do your best. Small play will not be visible, but can be felt with your fingers. If you like to play with tools, you can have fun hooking up that dial indicator and actualy measuring the slop. Try to do this with the wheels in the straight ahead position if possible, but it doesnt hurt to repeat the test with the wheels turned near to the stop point.

What is good about this method is that it tests your steering and some of your supension in the same position your car drives at, when you raise the car, some joints can stretch in their sockets and will pass a test that it would fail when properly loaded. It also is fast,easy and has the added benifit of involving your spouse/mate in something important to you.

A cracked boot does not mean a bad joint, but unless the boot was freshly ripped and no water or debris has entered the joint, it will go bad is its not already. The worst thing you can do, is look under your car, see a torn boot and decide that is the entire problem and not look any farther.

i retorqued all my lugs today and i noticed some improvement but it still occurs. I notcied it only happens at 45+ when the wheels are straight....if i turn the wheel even slightly left or right the vibrating stops...does that narrow it down?

It's your front suspension. I've tried retorquing the lugs, too, and get some improvement but the problem is still way too noticeable.

I've ordered the upper and lower control arms (with new bushings) and sway bar links from BavAuto.com for less than $500.