8" Pneumatic (Air) 280/250-4 Wheel Swivel Caster with Brake - 250# Cap - Mapp Caster
Waxman 12 in. 450 lb. Capacity Titan Pneumatic Plate Caster, Swivel, 4142955TD at Tractor Supply Co.
CasterHQ 10" x 3.5" Swivel of 4 Set Pneumatic Caster - 4 PLY - 350 LBS PER 1400 LBS PER Set Capacity - Air Filled - Commercial/Industrial Application 10 inch x 3.5 inch Shock Absorption: Amazon.com: Industrial & Scientific