Tires, Pro-Trax spiked 2.2inch (soft-compound)(rear) (2)/ foam inserts (2)SOFT COMPOUND 2.2 RACING TIRES: Soft compound rubber tires improve traction at the track. They are especially suited to hard-packed clay surfaces. Foam inserts help the tires to keep their shape. Rear tires feature sharp pin-spikes. Front tires are ribbed. Sold in pairs.