What is the wear pattern - is it even from inside to outside across the tread? Or is the inside or outside shoulder wearing faster? If either shoulder is wearing faster, the camber (how the
wheel leans in or out when viewed from behind the car) is incorrect.
If you run your hand along the tread front-to-back and then back-to-front, does it feel the same? (like petting a cat) If it feels smooth one way but jagged - like you are raking your had across a file or saw blade - then the suspension has a toe alignment issue.
If both shoulders are wearing fast, but the center region has significantly less wear, that indicates under-inflation. Verify your gauge is correct. Wear in the center of the tread but not on the shoulders indicates over-inflation: the tire is bulging out like a basketball.
A patchy wear pattern - as if somebody is randomly slicing off tread chunks - indicates a suspension that is oscillating vertically due to worn shocks or horrible bushings.
Vehicles with a true limited slip differential that is overly-tight basically act like a solid axle: when the car is going around corners, the outside
wheel needs to rotate a little faster than the inside
wheel; differentials allow this. Limited slip differentials allow it too but limit the RPM difference between the wheels. That way, if one
wheel is on ice and the other on pavement, when the
wheel on ice starts slipping like crazy the differential will tighten up and send power to the
wheel with more traction. Regular differentials (called "open differentials") will end up sending all engine power to the uselessly spinning
wheel. Genesis cars, with the traction control system, sense this and apply brakes to that spinning
wheel to force engine power to the other
wheel, electronically emulating a limited slip differential. Anyway, if a limited slip differential is too tight, acting locked up 100% of the time, the wheels cannot turn at different RPMs going around corners which creates all sorts of wear. Test: with the car on jackstands, transmission in neutral, parking brake released, try to turn one rear
wheel. The other
wheel should turn too. Now have a helper hold one
wheel still while turning the other. If you can't turn them independently the differential should be checked by a pro.
Also: when doing an alignment, many shops jack the vehicle up and then lower it onto the alignment machine. That lets worn suspension parts and bushings relax... so when the tech checks the suspension readout things look okay. But get driving on the road, with loads applied to the tire contact patches, those worn suspension pieces shift/move out of proper position. Driving the car straight onto the suspension machine, without jacking it at all, works better.
mike c.
