Your wheels may not be balanced, that's the single most-common reason. It's cheap to get them balanced, too. Just go to a tire shop and say "Hey, it's time to rotate and balance", they'll say "OK" and charge you 20 bucks or so.
If it still shakes, it's time to have the alignment checked.
If it only happens when you're putting on the brakes, your rotors are warped.
If it still shakes, it's time to have the alignment checked.
If it only happens when you're putting on the brakes, your rotors are warped.
