I put 2 new tires on the front of my Legacy, 9 mo ago. Rear tires are badly worn. Didn't know about the tire thing then. Tranny is tanking for other reasons, so not worried. Question, how many miles difference can one have on the tires? I've barely put any miles on the car at all since 9 mo ago....may be able to get away with adding 2 new tires to rear...plus new tranny. Hate to drop $300 for a matching set when the 2 front are so new.

Second question: can mismatched tires cause a "bearing noise" in the tranny...from the differential?

Thanks.

-Sarah

This is merely my OPINION, so listen to anyone that has the proper link to Subaru's info, etc.

 

It is not so much the miles as the difference in circumference, and I would expect an acceptable variance of 2-5%. (WAG!!!) One thing to consider is that tires that have the same nominal size (e.g. 195/70-14) might actually be a different height (and circumference) than the same size tire by a different maker or even the a different model in the same maker's line. Simple English: Try to make sure that you get the same exact tire as the ones that you are trying to match. It is (was???) possible to get the tread trimmed so it matches the older tires.

 

I would expect that the acceptable variance in circumference would be greater with the auromatic transmission than with the manual due to the different ways they accomplish AWD. The manual uses gears and such to send power to the rear tires, whereas the Auto uses a clutch-set (similar to what it uses internally to engage gears) and modulates whether or not this clutchset is engaged or not. Since the Auto's engagement cycles on and off, it SHOULD tolerate tire circumference differences better.

 

My answer to your question: Find 2 matching tires (maker/model/size) and you should be OK. I would have the store check the difference in tread depth just to be sure.

Thanks. I also think I read somewhere that someone had done measuring and found that if the tires...same brand, style, size...were within 10,000K of each other it was okay. I am hoping I remember that correctly. I think I can still buy the same style, since it wasn't very long ago.

No, not the stated tire size, but the actual circumference needs to be within a certain range of the other tires. I seem to recall that it is either 1/4 or 1/2 of an inch in circumference.

 

I had an accident and trashed one tire. The tires had 30,000 on them. The other insurance company did not fight me on them paying for a new tire and also more money to have the new tire shaved to the right size. Shaving is actually turning the tire (like on a lathe) and removing tread, so it is the same size as the others. I took the money and invested in replacing the OEM RE92's because I didn't like them anyway, but that's a different story.

 

It's important to the life of your viscous clutches to have similar sized tires and therefore similar wheel rpms.

 

Jack

My grandfather drove his 1980's Buick for six or seven years, and never bought a new set of tyres. Whenever he got a flat or had a tyre that was balding severly, he would go to a gas station, look through the re-treads, and buy whatever he could fit on the rim and whatever was cheapest. The car was drivable, but when no tyre on the car is the same, you can definately feel it going down the highway, or any street for that matter. You can run differently sized tyres, but I wouldn't recomend it though.