mismatched tires

[sexwagon]

I blew out my right front tire one day trying to keep up with my buddy on a dirt road on his dirtbike. I hit a rock in the road and it put a hole in the sidewall. Anyway, i put the pointless little donut tire on and got it home, and i just happened to have a pair of wheels/tires off of my brother's old chevy celebrity that bolted on. I figured they had to be better than running a donut even temporarily, even though they are one step larger in diameter than the stock tires.

I hadn't really been driving the car after that, so i didn't really worry about it and it just sat in the driveway like that. Until my brother needed to use it for a week to get back and forth to work. He was supposed to get the tire replaced (junkyard has em for $10 a piece, the cheap bastid lol) before he drove it much, but he didn't and now the car has a hell of a vibration going on.

Now it's just sitting in the yard again all pissed off looking with celebrity rims on it telling me to figure out what's wrong with it NOW. I have a tire the right size to mount on it, but if it still vibrates, WTF do i do? The AWD is still functioning (not that i will pretend to know jack **** about it) so i don't know where to start.

[Hitokiri]

I'm not going to pretend like I know much, but first step is to put on the correct sized wheels and tires. With most AWD cars, you're supposed to replace every single tire at once, just for miniscule differences in tire wear. The newer WRX's you don't have to, but I'm not sure about the older ones.

From there if it continues, I'm pretty sure you need a new diff. If it suddenly just started, pretty sure you overstressed something.

[A1337STI]

Sounds like you may have damaged your center diff. :( its possible the damage is in the front or rear diff though.

you could start with putting your car on jack stands and try out first and make sure all 4 wheels still spin. see if any of the wheels or axles has an obvious shake / vibration.

[sexwagon]

thanks guys, i guess i'll get the right tires on it and go from there. :shootsself:

[whitt]

I'm going to have to second the diagnosis of a blown centre diff. With different size tires on the front and back you will have forced the diff into a situation where it needs to slip all of the time. Essential you have changed the gearing on one set of tires and not on the other so you are now driving them at different speeds.

I hope I'm wrong and this is not the issue, at least it is better than a blown front diff....