Vehicle rutting is a measure of the impact of a vehicle on the terrain. This study investigated the influence of vehicle type, vehicle weight, soil conditions and turning on soil rut depth and width. A vehicle impact study was conducted on two tracked vehicles (M1A1 - combat tank and M577A2 - armored personnel carrier) and two wheeled vehicles (M998A2 - heavy expanded mobility tactical truck and M998 - high mobility multi-purpose wheeled vehicle) on October 19, 2004 (dry conditions) and April 12, 2005 (wet conditions) at Fort Riley Military Installation, Kansas. A Differential Global Positioning System (DGPS) was used to track vehicle movement while conducting sixteen spirals per vehicle (except for the HUM-V with fourteen spirals performed); four at fast speeds and four at slow speeds on two different soil types at two soil moisture conditions; wet and dry. The GPS was used to determine the vehicle speed and turning radius along the spiral. Rut depth and width were evaluated at 891 points along the sixty-two spirals. The influence of vehicle type, vehicle weight, soil conditions and turning on soil rut depth and width is investigated.