The correct use of tires, as for its construction type as for internal pressure calibration and the optimal weighting for each load condition are factors that impact significantly on their performance. This study aimed to compare the performance of a tractor equipped with radial tires and bias ply tires in three conditions of liquid ballast (0%, 40% and 75% water), three surface conditions of a Dystrophic Red Alfisol (firm surface, tillage surface and surface with corn residues coverage) and three theoretical traveling speeds (4 km h-1, 5 km h-1 and 7 km h-1), as indicated at the tractor display, related to the gear boxes B1, B2 and C1. The best tractor's performance, equipped with bias ply tire happened at 75% water in the tires and it had provide a higher traveling speed, lower slippage, lower fuel consumption per hour and higher drawbar pull power. The radial tires with the best performance happened at 40% water in tires and it has provided a higher traveling speed, lower slippage, lower fuel consumption per hour, lower specific fuel consumption and higher drawbar pull power bar.
trative efficiency; agricultural machinery; tractors test
