It could simply be that your wheels need to be properly balanced. Also, if your alignment has caused cupping or feathering in your tires--that could also be the problem.

Lift the front off the ground. Try to wabble the tire from left to right. It may move a little, but there shouldn't be any "slop." If there is slop, look into tire rod ends.

Then try to wabble the wheel up and down. If it moves at all, inspect your upper and lower ball joints.

If the car has been wrecked. Inspect all control arms and bushings. Bent control arms should be replaced immediately, along with their connecting bushings. If you have any dry rotten or squished bushings, replace them. Don't dare align a car with these symptoms. You will waste your money.

Don't pay someone to do this. It's easy.

Now, go get new tires if your current ones are severly worn.

Don't get an alignment with worn tires. It can throw off the geometry. If you can't afford new tires. Get used tires that have similar tread life left, and avoid tires with unevem wear.

Finally, get an alignment. If your car is lowered beyond idiocy, go to GTE for an alignment. They are usually okay with lowered cars, given the said car has adjustable aftermarket control arms that will compensate the differences.

Good luck.