Shade tree mechanics used to use hand tools to remove car tires from tire rims and replace them. Modern, tubeless tires require special machines and tools that push, pull and lever the stiff tires onto or off of the rim. Most shops specialising in tire repairs have pneumatic powered tire machines to do the work. Hand operated machines are available for people who only occasionally need to mount or dismount a tire. With either kind of machine, the steps necessary to accomplish the job are similar.
Use a valve stem tool to remove the core from the valve stem to let all the air out of the tire being changed.
Mount the tire solidly to the tire machine by positioning the tire onto the centre support bar and then tightly screwing on the cone shaped nut that threads onto the support bar.
Remove any wheel weights from the rim of the tire with pliers.
Actuate the bead-breaking mechanism. On a pneumatic machine a plunger pushes down on the top side of the tire and another plunger pushes up on the bottom bead simultaneously loosening the both the inside and outside beads from the rim of the wheel. On a manual machine, the bead-breaking lever will do the top bead first, after which the tire has to be removed from the machine, turned over, repositioned on the machine and the lever is pulled a second time to loosen the bottom bead of the tire.
Insert the tire dismount arm between the bead of the tire and top edge of the rim. Connect it to the support bar then actuate the mechanism, which causes the support bar to turn, rotating the dismount arm. As the dismount arm rotates, the bead of the tire is stretched up an off of the edge of the tire rim. On a manual model, once the dismount arm is in place between the tire and rim, the centre support bar is used as the fulcrum, as the dismount arm is manually levered around the edge of the tire lifting the top bead of the tire up and over the top edge of the tire rim.
Lift up the tire high enough the dismount arm can be inserted between the top edge of the tire rim and the bottom bead of the tire. On a pneumatic machine, the dismount arm then is again levered back to connect it to the centre support bar, the support bar actuator is pushed and the dismount arm rotates around the rim stretching an lifting the bottom bead of the tire off the top of the rim. On a manual machine, the centre support is again used as a fulcrum and the dismount arm is levered around the rim, removing the tire from the rim.
Wet down the lower bead with soapy water. This isn't to clean the tire, it's to lubricate it to make it slide onto the rim easier and without cutting the rubber.
Set the new tire on top of the rim, pull it to one side, then slip a part of the lower bead over the edge of the rim.
Set the mounting arm in place contacting the rim and the bead of the tire right where they touch at the edge of the tire rim.
Connect the mounting arm onto the centre support on a pneumatic machine and touch the actuating mechanism so the mounting arm rotates around the rim of the tire stretching and pushing the bead over the edge of the rim. On a manual model, push the mounting arm against the centre support using it as the fulcrum as you lever the mounting arm around the rim of the tire, stretching and pushing the bead of the tire onto the rim.
Lubricate the top bead of the tire with soapy water.
Push a part of the top bead of the tire over the rim and position the mounting arm.
Connect an air hose to the valve stem and add air until the air pressure pops the tire into position on the rim.
Reinsert and tighten the valve stem core and then add air until the correct pressure, measured with a tire pressure gauge, is attained.
Things you need
- Valve stem tool
- Tire machine
- Cone nut
- Bead breaker
- Dismount arm
- Mounting arm
- Air compressor
- Soapy water
- Tire pressure gauge