If you haven't had it done in awhile, get those wheels aligned and balanced... even if everything feels fine, a very slight offset can slowly turn bigger. It amazes the hell out of me how many people turn in their lease cars at my work with 20-40,000 miles and the suspension is just shot to hell, squeaking, rumbling tires, popping steering, horrid looking tires. Its like, Bajesus... It just takes $60.00 once a year for a rotate, balance, and alignement; it isn't that freakin bad! Instead, they'll be paying hundreds in repair bills when GM gets their car back.
Hmm, probably a given... check your tire pressure. Its getting warmer and the tire pressure is changing.
