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1, 2, or All 4 Lightly Used Tires to Replace for AWD?

So just today I found out my Subaru Forester 2006’s rear-left tire was flat. Filled it up and took it to Firestone nearby and they found a nail lodged in the shoulder of the tire. Since this cannot be patched and must be replaced, and although I understand AWD’s should have all four tires swapped out when a blowout occurs, I got these tires new just about 5 months ago and put not even 4,000 miles on the car with them.

Could I get away with just replacing the one blown-out tire with the same model, should I replace both on the rear axle, or does the amount of use on them not matter and all four should be replaced anyway? Thanks.

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4k miles it not much, I had the same thing happen, different make but got one new tire of the same model. 2wd, and 4wd auto or low hi. Somebody more familiar with the tolerences should be contacted, but a tire dealer can measure your tread depth vs new, then a call to Subaru and see if the tread depth differences are acceptable.

I really do not know the tolerance limits for AWD. Two thoughts, one find a tire dealer that can shave the new tire to the same wear as the other three. Or mount the tire at the position of greatest wear, to my mind the left front. Then go back to the routine 5000 mile rotations.
Warning: I’m NOT an expert!

Replace the tire

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4k miles of wear is insignificant enough that you can safely replace just that one tire.

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I’d just replace the one tire too. Note that @VDCdriver is a long time Subaru driver and understands the AWD implications of mismatched tires. When he says it, you can believe it IMO.

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Yup!
Three, and counting…

Why guess when the manufacturer specifies what is acceptable. All that has to be done is measure the tires and compare to the allowed deviation spec. I suspect you’ll be fine replacing one but when it’s so easy to be sure and the ramifications for guessing wrong are high…

The “by the book” tolerance is 1/4" between the largest circumference and the smallest. If all the tires are the same brand, make and model, then that translates to about 1,5/32" or just over 1/32" tread depth. You can buy a mechanical tread depth gauge at any parts store for around $5. If you are in tolerance, which you most likely are, then just get the one tire.

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I sent an e-mail to my contact within Subaru today. I will share the answer with the group if I get one. Here is what I sent , edited a bit for clarity:
“A common conversation at the Car Talk Community relates to replacing a single tire when one is destroyed on a Subaru vehicle equipped with AWD. Can you offer some guidance on this subject? …I would also like to know if the guidance is the same for all Subarus with AWD, or model and year specific.”