Step 1
Examine the rusted area to find out how severe it is and where the bulk of the rust is. Inspect to ensure the tire rotates freely and is merely stuck on the axle. Brush away as much of the rust that you can.
Step 2
Squirt the area where the wheel and axle meet throughly with a penetrating oil or light machine oil. Allow the oil to sit for at least 30 minutes. Very heavily rusted areas might even need to sit overnight.
Step 3
Brush the area clean of rust with the brush. If the rust does not come loose, thoroughly squirt it again and wait some more.
Step 4
Remove the wheel. Each lawn mower manufacturer has a different method of attaching the wheels; consult your owner's manual. The most common method involves peeling off a C-clip, snap ring or a cotter pin next to a flat washer from the axle with a screwdriver, which releases the wheel, allowing it to slide off.
Step 5
Tap the wheel and axle gently with the hammer if the wheel does not come off after the retaining device is removed. Do not hit it hard because a lawnmower axle is not the sturdiest piece of machinery in the garage.