Tires The Caterpillar 797 series haul trucks run on the largest tire in the world, the 4.028 m (13.22 ft) tall, 5,300 kg (11,680 lb) Michelin 59/80R63 XDR. This radial tire was developed by Michelin in conjunction with Caterpillar specifically for the 797. Six tires are required per truck at a