Element Empty Weight (Ib) Percent Loaded Weight (lb) Percent Drive Wheels 50,800 67 76,900 52 Scraper Wheels 25,000 33 70,900 48 Total Weight 75,800 100 147,800 100 Table 12.5 Coefficients of Traction Materials Rubber Tires Tracks Concrete 90 45 Clay loam, dry .55 90 Clay loam, wet 45 .70 Rutted clay loam 40 .70 Dry sand 20 .30 Wet sand .40 50 Quarry pit 65 55 Gravel road (loose, not hard) .36 .50 Packed snow 20 25 Ice .12 12 Firm earth .55 .90 Loose earth 45 60 Coal, stockpiled 45 60