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Replacing Tires on a Subaru

Hello Mechanically-Minded Individuals! I have a conundrum that I need a third opinion about. I own a 95 Subaru Outback. Last time I had to have a tire replaces, I was told by the guys at the tire chain that I needed to get all four tires replaced at the same time, or suffer dire consequences. I went again and got a whole set of new tires. I recently had to replace another tire and was told the same thing. Another friend of mine, who’s not a mechanic but is a mechanical engineer that worked for NASA for 19 years, said that that was utterly ridiculous and they were just trying to sell me four tires, rather than one. I’m financially strapped now and it would be a real burden to have to purchase the remaining three new tires in the next couple of weeks, but I also don’t want to jeopardize the integrity of my trusty car. Is it possible that Subaru is in cahoots with the tire companies and therefore preaches this spiel to all tire chains just to make money? Any advice would be appreciated!

The Subaru AWD system is particularly sensitive to differences in tire circumference. If your tires are near-new, replacing one won’t make any difference, but if they’ve been on the car for a few years and are partially worn the new tire could cause a problem.

The AWD transfer valve and clutch pack in the automatic transmission can be adversely affected by tires of different size front to rear. This was a $750 repair bill when I found out about it the hard way.

Tires are cheaper.

Find a similar tire with an equal amount of wear on it; that should cost you no more than $25 or so. On a Subaru, keep all the old tires when buying a new set; that way you may be able too re-use some in the future if they have the same amount of wear on them.

If the remaining tires are in decent shape, the tire shop should be able to SHAVE the new tire down to match the wear on the three remaining tires. This will effectively reduce the life of the new tire but save you from having to replace all of them. If these guys do not know about this or have the equipment, call around to the larger tire stores until you find one.

All of the preceding answers are correct, and your friend is wrong, wrong, wrong.

I can understand that you are looking for a low-cost answer since money is tight right now, but the only low-cost answer is to do as Twin Turbo suggested, and to buy one tire that the tire retailer “shaves” to the same circumference as the 3 old tires.

If you prefer to go with wild conspiracy theories, then you will just have to learn the hard way that it is not a good idea–financially speaking–to ignore the advice of those of us who do know about this topic (unlike your NASA friend).

Incidentally, if you take out your Owner’s Manual, you can read the information relevant to this topic that was written by the people who designed and built your car. You will find that, while it is not as detailed as our responses, it also cautions you against doing what your friend advised you to do.

Hi All. Thanks so much for all of the input. It’s really helpful. Based on all of this information I’m convinced that I just need to bite the bullet and buy all new tires. Your advice is much appreciated! : )

Good decision, Tiffany!
Please remember to rotate those tires on a regular basis–every 5k to 7.5k–in order to equalize the wear on all 4 tires, and to keep them inflated to at least the pressures listed on the label affixed to the driver’s door jamb. Note that the rear tires take slightly less pressure than the front tires.