I've got an '01 Legacy and I'm riding on worn 205/65 r16's on the front and newer 195/60 r16's on the rear. I'm thinking it's time to replace the front tires. Most places on the internet (which don't have people as knowledegable as ultimate subaru) say that I absolutely must change all four tires and have them inflated at exactly the same pressure all the time or my center differential will blow up.

 

I'm a cheapskate so if I can only buy two I'd like to. And if that means I might have to drop $1000 later a new differential I'd rather not. What should I do?

you should at least have the same size all the way around.

 

what should you do? replace the old tires with ones the same size as the remaining ones.

That's not really good. If you don't have torque bind already, it is at the least putting excess wear and tear on the AWD components (what exactly depends on whether it is a manual trans or auto trans).

 

Subaru wants the tires to be all within 1/4" circumference.

you could put in the FWD fuse under the hood and I guess use any mix of tires you want.

the way the AWD works - you can hose the transfer clutches and more (automatic) or center diff (manual). actually - you *will* cause them to fail every single time the circumference or rotations are not congruent - it's just a matter of how long and when.

 

the circumference is what matters - most folks aren't mechanically inclined or have the capacity to figure this stuff out - so the simplest one size fits all approach is to have all tires matching.

 

places around here typically install two new tires by putting them on diagonally on subarus - one on one side rear, one on the toher side front. i wouldn't do it, but it's done enough around here that there must be a reason.

 

you gotta be smart but you can work around things.

trans probably has lots all the funcitoning part of AWD by now if you ran those tires for more than a few weeks.

or mix your existing tires diagonally. the steering will be weird, but this will help with spreading rotational difference across the differentials with your existing tires.

best to put odd size up front left, the front diff is open and it will keep the issues down by having it up there.