I just had a similar thing done on my Outback at Discount Tire last month and it was ~$90. Are they charging more for offroad tires? I think I was charged for "winter tire changeover" and "TPMS service". Really all they are doing is popping the bead to remove tpms on 5 tires then popping the bead to install tpms and balancing. Technically they did more work on mine since they had to mount the new set of tires (not bought from them) too.