A RADIAL tire is a type of tire that has the cords of the carcass layer running at 90 degrees to the direction of travel. A RECAP tire is a tire that has been re-capped with a new tread and sidewall after the original tread has worn down. A RETREAD tire is a tire that has been re-treaded with a new tread after the original tread has worn down. A SPARE tire is a tire that is kept as a backup in case of a flat or other emergency.