This is a NOS (new old stock) vintage Barum  off road knobby tire, size is 2.50-21  S23. 

Great for your vintage motorcross bike, or AHRMA racer.  Penton / Husqvarna / OSSA / Hodaka / KTM / Honda / Kawasaki / Yamaha / Suzuki / Sachs / BSA / Triumph / Norton / and many others.
 

It has been in an environmentally controlled warehouse for several years. Tire has been sitting on a shelf, a little dusty and dirty but no dry rotting or cracks.    Great for that restoration project bike.