This paper discusses the results of testing variable tire pressure in two of Weyerhaeuser's logging operations in Western Washington. Ten log trucks had prototype Eaton central tire inflation systems installed, five at Raymond and five at Vail. The trucks were involved in cooperative testing with the U.S. Forest Service and the Universities of Washington and Idaho. A test at Raymond, Washington compared high and low tire pressure on roads constructed from weak sandstone rock typical of the Southwest Washington coastal area. The test showed a significant improvement in traction and a reduction in road maintenance with low tire pressure compared to the high tire pressure. A test at Vail, Washington evaluated the effect of low tire pressure on varying surface thickness. Low tire pressure trucks were able negotiate 18 percent adverse grades unassisted, with loads exceeding 43,000 kg. The road withstood 447 passes with as little as half of the normal surface thickness, with minimal road maintenance. In both locations, a significant improvement in ride comfort to the drivers and faster return travel time was experienced. Tire tests have shown no significant change in treadwear rates on original tread, but a possibly significant reduction in road hazard damage.