The Thunderer OA421 is a versatile mixed-service semi-truck tire that's built for use in regional and long haul applications. The OA421 features a heavy-duty, damage-resistant tread compound that's designed for good heat dissipation, an on- and off-road tread pattern, retreadable casing, and an up to 20 ply rating. Features & Benefits Designed for use on mixed-service semi-trucks in regional and long haul applications Tread pattern allows for better performance on- and off-road Rubber compound guards the tire against cuts, chips, and abrasions that are common with on- and off-road driving Engineered to dissipate heat to prevent irregular wear High ply rating for extra strength and durability