This is the tire set we use in the Luna Deluxe wheel set for Surrons and Talarias

You must already own a 21/18 wheel set with 21 and 18 inch sized rims to use this set. 

21 inch for the front 18 inch for the back.

This is for the tires only. 

Front  80/100  3.1.  21inch   Rear: 90/90 3.5. 18 inch

Made from a soft compound for exceptional grip especially when riding off road.