A pretensioned spring track tensioning system provides a two stage loading of a tension roller on the interior of a vehicle drive track. The two stage loading first loads the track under a lower tension load for normal operation, but when the track is highly loaded, such as when digging, or when debris is forced between the track member and its drive sprocket or guide rollers, the compression of the lighter spring will be stopped mechanically and a second heavier compression spring will provide the tension loading. The additional spring tension under unusual conditions prevents detracking of the track and buckling of the track. A lighter tension load during normal operations reduces the loads on bearings, particularly in relation to a drive motor. The tensioning system has particular adaptability to “high” drive type tracks which have a drive sprocket elevated above the tension roller.