Tyre 'out of round'

Gil, search for lots of threads dealing with size differences when replacing tires. This comes up VERY often. You also don't mention how old this set of tires is, how much difference there is in CIRCUMFERENCE between the 4 tires. Subaru's specifications, for what little they are worth, say you cannot have more than 1/4" difference in circumference. That's a VERY small amount, and many of us have been in situations that forced us to either go along with it, costing us a set of tires that were not very old, or else taking the risk and using a single new one that was more than 1/4" off from the others. I did this with about 3/8" difference and have no knowledge of problems because of it (that was probably well over 25,000 miles ago.) This is going to be a judgement call on your part, but only you can decide whether the cost is worth the risk. Some here would say it is not much of a risk at 3/8" but others would say it's always a risk. I can't answer that for sure, but I do believe Subaru's specs are overly tough, and hard to achieve in the real world. They'd like to have an "out" if you do have drivetrain problems caused by this, however, and the specs give them that. Best of luck to you.

If you get a new one, you can get it shaved so its circumference matches that of your other three. Utility of this depends on the life of the remaining tyres.

At least this is done at speed shops in the USA.

Al