... Blocks center of the tread, wide grooves on shoulders. Good for rigid roads, great grip in gravel conditions, self-cleaning ... damage and open shoulder design enhanced self-cleaning, excellent for gravel road like mines.Size Ply Rating Load IndexSpeed Code ... /149F8.0032503550930109629312.00R2018154/151F8.5034503750830113631512.00R2020156/153F8.50365040009001136315 tires for trucks 1100R20 1200R20