No matter how often you cut your lawn, or what kind of terrain you drive over, you lawn mower tires will eventually need to be changed. If they are bald, have too many plugs, or show signs of localized wear, it is safer to change them than to use them in a compromised state. Changing a riding lawn mower tire is not difficult, and doing the job yourself will save you quite a bit of money. No specialized tools are required.
Park your mower on a flat, hard surface such as a driveway. Engage the parking brake.
Slide the floor jack beneath the middle of the frame in the rear of the mower if you're changing a rear tire, or beneath the middle of the frame in the front of the mower if you're changing a front tire.
Chock the front tires if you're changing a rear tire, and the rear tires if you're changing a front tire.
Loosen the lug nuts on the bad tire slightly, using a socket wrench or an impact wrench.
Raise the mower approximately 1 foot off the ground.
Continue to unscrew the lug nuts, removing each one. Slide the tire off the hub.
Position the new tire on the hub, and hand-tighten each lug nut.
Tighten one nut with the socket wrench or impact wrench. Then move to the nut opposite that one and tighten it. Continue to tighten nuts opposite each other until they are all snug.
Lower the mower to the ground and tighten each nut again. Remove the chocks. Release the brake.