To provide a pair of front and rear wheels that hold a basic performance of an off-road motorcycle and further improve a traction performance and a shock performance, and its mounting method.

A rear wheel tire includes a call of a rim diameter subtracted by 2 from a call of a rim diameter of a front wheel tire. In an actual using state, for a tread curvature radius of a treat central region with at least 30% width of maximum tread width, a ratio CRf/CRr of a curvature radius CRf of the front wheel tire to a curvature radius CRr of the rear wheel tire is in a range of 0.45-0.90, the rear wheel tire has a smaller oblateness than that of the front wheel tire, difference between the oblatenesses of the front wheel tire and the rear wheel tire is in a range of 10-35%, and the rear wheel tire has 80% or less oblateness.