More wear on the two edges is typical of under-inflation, but from what you've described, it sounds like there's more going on here, and it's more than an alignment problem.
Only two things can cause excessive wear on JUST the inside of the tire. One is too much negative "camber", meaning the wheel is tipped in on top. That makes the tire ride on the inner edge. Camber affects just that one tire, but camber can be off on the other wheel too. Camber also affects pulling to one side when you let go of the steering wheel. The camber setting on both wheels has to be very nearly the same so their pulls offset each other and the car goes straight.
The second thing is "total toe". That is the direction the two wheels are steering. Negative total toe is when the two wheels are steering away from the center of the car. The left wheel is turned to the left and the right one is steering to the right. Regardless if one or both wheels is misadjusted, total toe always affects both tires equally. This condition will cause excessive wear to both inner edges but there is usually also a feather-edge pattern on the tread. If individual toe is off an equal and opposite amount on the two front wheels, the steering wheel will still be straight, but there will likely be a lot of steering wander on the highway.
Where things get more complicated is when you have multiple symptoms like you described. To go through tires in a few months is proof there is a serious alignment issue, and that is almost always accompanied by other symptoms including clunks and rattles. The best approach is to start with a steering and suspension system inspection at a tire and alignment shop. Based on your description, I'm betting they're going to present you with a long list of worn parts, some of which can be dangerous.
Wednesday, January 1st, 2014 AT 1:06 AM