Here's the deal, many a Subaru owner messed up their center diff by having mismatched tires and didn't know it until their car had lousy traction in the snow because the vehicle was now front or rear wheel drive, depending on the mood.
I'm surprised that they didn't know it, the steering will bind when turning with tires that are mismatched enough to make the diff unhappy.
I've always been careful about running tires within 2/32" of each other on my Subaru, but my center different still went bad at around 200k. When my transmission was warm, I'd get a loud clicking noise when turning at lower speeds. Wasn't the cv axles either, was very much temperature dependent, new center diff fixed the problem.