Riding lawn mowers typically have tires that are inflated with air just like car tires, although they are much smaller. Just like car tires, after normal wear and tear, the tires need to be replaced with new ones. Removing riding lawn mower tires is a little easier than removing a car tire since the lawn mower is much smaller and much lighter, but the same basic principles apply.
Raise the lawn mower tire off the ground with your jack. Make sure it's on a smooth, level surface when you are jacking it up.
Remove the rubber boot that covers the spindle. Grab it with pliers and gently pull it off.
Look for a "C" clip. Use a flat-head screwdriver and gently pry the clip off. Don't apply too much force at once or the clip will fly off and get lost.
Take the tire off of the spindle. It should just pull right off with ease. Replace with a new one.
Push the "C" clip back into place with your screwdriver. Your tire should now be secure on the riding lawn mower.
Put the black rubber boot back on by stretching it over the spindle and pushing it back into place. Lower the jack.