This video shows a 21L-24 R-4 backhoe tire being mounted on a Caterpillar wheel using Ken-Tool's brass bead holding devices (No. 31710). The bead holders keep the bead from slipping up over the edge of the wheel while working the bead around the tire. Ken-Tool's bead holders are made from brass to avoid scratching paint or chrome/alloy wheels. Try to do that with locking pliers.