well. Six tires are required per truck at a cost in 2009 of approximately US$42,500 per tire. Manufacturing and assembly Major components of the 797 are manufactured and assembled at seven Caterpillar or supplier facilities located throughout North America, then shipped to the customer site for final assembly by Caterpillar technicians. The engine is manufactured by Caterpillar in Lafayette, Indiana, and is then shipped to Caterpillar's assembly plant in Decatur, Illinois. The transmission and torque converter are manufactured by Caterpillar in East Peoria, Illinois, and is then shipped to Caterpillar's assembly plant in Decatur, Illinois. The axle assemblies are manufactured by Caterpillar in Winston-Salem, North Carolina, and are shipped to the customer site. The tires are manufactured by Michelin North America at the US7 Earthmover Manufacturing plant in Lexington, South Carolina, and are shipped to the customer site. The driver's cab is manufactured by Bergstrom Climate Control Systems' Contract Assembly division in Joliet, Illinois. Each cab is assembled by one person and requires forty hours to complete. The cab is shipped to the customer site. The dump body is composed of five components: the floor, the two sides, the front wall and the canopy. The dump body is manufactured at Caterpillar Mexico in Monterrey, Mexico, as well as at least to a limited degree by WesTech of Casper, Wyoming in the western United States and shipped in component form to the customer site where it is assembled and welded into a monolithic structure before being joined to the frame during final assembly. The frame is created from nine individual metal castings manufactured by Harrison Steel Castings Co., in Attica, Indiana and by Amite Foundry and Machine, Inc., in Amite City, Louisiana. The smallest casting weighs and the largest casting weighs . The rough castings are shipped to the Caterpillar Decatur, Illinois, assembly plant. At Caterpillar's assembly plant in Decatur, Illinois, the frame is assembled and the powertrain is installed and tested. The nine castings that compose the frame are machined to provide clean welding surfaces. The castings are placed in a jig and are initially joined by human welders. The frame is moved to a second welding station for further welding by robots. The third and final welding stage is completed by human welders. To ensure quality, welds are tested using an ultrasonic flaw detector. In total, of welding wire is used to join the individual castings into a monolithic