First, loosen the bolts on the tire. Do not remove the bolts; just loosen them.
Find a spot on the vehicle that can be supported by a jack and raise the vehicle.
Remove the bolts and tire.
Put on new tire, and tighten bolts but NOT to try to tighten bolts completely. Just tighten until decent resistance is given.
Lower vehicle on jack. Tighten bolts as much as possible. Done!