Tires

You need two new ones, one on each side. You can run the other two until they need replacement.

Just do the two

Replace all four if the other tires are worn a lot as you may damage the AWD by running tires that are different diameters. Your tire shop will probably know the size difference that Subaru allows.

Subaru states that the tire treads be within 2/32" tread depth (this would be for a matching set of tires, not mixed brands) . They also say that the tire circumference be within 1/4" of each other when measured at the tread center.

Quite a bit of lee-way on the diameter, 1/4" also 2/32 = 1/16".

Rowe, that is circumference, not diameter. 1/4" in diameter would equal about 3/4" difference in circumference.

Yea, that makes a big difference, 1 & 1

I had a similar issue on our 2011 Forester XT. Service shop could not repair the tire said I had to buy all 4 new tires. I did some internet searching. Found bestusedtires.com. I was able to find a replacement tire with the same amount of wear. They even have photos of the tires so you can visually compare the wear on the tires so you know it is a good match. This worked so well. That I bought a whole set when I needed new tires for a slightly used set for about the price of one new tire. Awesome. Highly recommend it when you need one tire or need a whole new set. Why pay full price for new. Just get cheaper used goood tires, just won’t have as many miles on them.

My wife picked up a piece of metal in the sidewall of our 2020 Ascent recently. The vehicle has only 12,000 miles on it. I replaced the damaged tire with a new one. Now the dealership is saying I need to replace all the tires. Is this correct??

That would depend on how worn the other tires are. If you have a drivetrain problem the dealer will void your warranty. They gave you warning!

Call around and see if you can have the new tire shaved. The Tire Rack can do it.