The Firestone 300-21 motorcycle tires are an excellent fit for choppers, custom motorcycles and race-inspired bikes using a narrow twenty-one inch front wheel. These Firestone Ribbed 21 inch Motorcycle tires have a straight-groove tread pattern and a simple sidewall design. These are a great vintage look for any custom motorcycle with a 21-inch front wheel. Coker Tire Company caters to custom motorcycle builders around the world with several Firestone product offerings for vintage and custom bikes.