Assuming you don't have a flat tire already, you will need the following tools to change a lawn mower tire:
-jack
-jack stands
-wrench (for removing wheel bolts)
-spare tire
-tire iron (for changing the tire)
1. Park your lawn mower on a level surface and engage the parking brake. Place blocks behind the rear wheels to prevent the mower from rolling while you're changing the tire.
2. Use your jack to lift up the front of the mower until the tire is off the ground.
3. Remove the wheel bolts with your wrench and then remove the wheel from the axle.
4. Put your spare tire on and hand-tighten the wheel bolts before lowering your jack and tightening them fully with your wrench.