Tractive performance comparisons among five different size tires were made on two different surface conditions, a wheat stubble field and a tilled wheat stubble field. Radial 18.4R46, 20.8R42 and 710/70R38 radial tires; and bias 750/65-38 and 850/55-42 tires were used.
Instrumentation to evaluate tractive performance was installed on a two-wheel drive and a mechanical front wheel drive agricultural tractor. Axle torques, drawbar pull, travel speed, and engine rpm were recorded for a series of drawbar pulls on the two soil surfaces.
Tractive performance evaluations among the tires were made by comparing the relationships of dynamic traction ratio to slip, tractive efficiency to slip, and tractive efficiency to dynamic traction ratio.
In general, narrower tires exhibited performance advantages over wider tires.