What causes my 98 chevy silverado to shake with my 20" wheels?

Well it's not easy at times to even tell if a rim has a slight dent or warp in it and many times the tire specialists don't catch any faulty rims or even a faulty tire although it was balanced.Now if you had switched tires around say from the back to the front and now had a wobble on the front many times slight wobbling in the rear end isn't noticed until these same tires and rims are on the front end of the vehicle. If you had no wobbles before you had this work done then it's obviously something related to the chances made but if the vehicle did have already a slightly loose front end you may now notice it a lot more. Hope that helps and best of luck.By the way I was out this summer on vacation and while there I decided it be a good time to rotate and balance my tires so to save labour why not get the tires balanced and they can rotate them easily once on hoist.So I had them balanced switched from back to front and drove off now suddenly when on hwy going 100 kms an hr or over the car vibrates like crazy.I was thinking to myself what the heck is going on here then I thought well I've already had these same tires and rims on the front end last yr and no wobbling it must be that the mechanic using the balancing machine at the shop messed up badly.Since I had already driven several miles from the shop and it was about to close I went to another shop close by lol.When I got out I noticed that one wheel had no weight on on the rim that should be there.I asked the Dodge dealership to check the wheels for alignment and when we got into talking about it , it was obvious to us that the previous mechanic used probabbly the wrong weights on the rims.Well I was right that the alignment job had be spoiled and once this shop balanced them the ride was very very smooth at any speed. That's not the first time I've run into improper balancing of tires I've seen it many times and know many many ppl that also have had the same type of problems. I recommend that you have another mechanic check just even one of the front wheels for balancing and if you find it off go back to the ppl that balanced yours but be sure you have both the tires check on front for possible warps or bulges etc.

i had the problem on my ford.i had to change the tires to the other side of my truck.i rotated the left to the right sides and i never had the problem anymore.maybe you should try that.hope it work's for you.like it did for me.

Might be that your Boom Box is too loud. Turn it down.