There is a product we use to seat our beads called Phoenix bead sealer, DO NOT use the "fill with gas and light it" method. That is a good way to get burned. We bought a fairly inexpensive electric/air tire changer from Greg Smith equipment in Indianapolis and buy our trailer tires 10 at a time. The machine changes mower tires as well as truck and trailer tires. It takes literally one minute to remove a tire and replace it. We considered not only the money we were spending to have someone change our tires, but the time involved in running the tires back and forth to their shop.
Just cutting the grass just doesn't cut it.