Tractive performances of four commercially-available models of lawn and garden tractor drive wheel tires were compared in field tests involving vehicle operation on turf surfaces. Tires were mounted on two small tractors which had been outfitted with comprehensive instrumentation systems, allowing measurement of wheel slip, vehicle pitch, and draft force, plus several other parameters. When the four sets of tires were operated on a level surface, significant differences among the tires based upon measures of average drive wheel slip were revealed. Average drive wheel slip was actually reduced when water was sprayed on the grass surface. For slip levels below 20 percent, drive wheel slip tended to increase at an increasing rate as the magnitude of drawbar loading was increased. Type of tire was not shown to have a significant effect upon the slope angle at which spinout occurred when the test vehicle was driven up-slope in reverse gear.