James-

In my experiance working for a Subaru dealer, I must direct you to make sure you have a matching set of 4 tires. Your tires should be all of same brand, model, size, and tred pattern. The tredwear should also be nearly identical. Subaru recommends that you measure the circumference of the exterior of the tire. If the difference between any two tires is more than 1/4" the tires should be replaced. I've seen some transmissions, especially 4eat's that have been seriously harmed by mismatched tires.

Although adding the other two tires seems like a great expense now, it's nothing compared to the damage that could be caused to your transmission.

Best of luck to you, James!

Mike