On the Suzuki 250 4x4, the back tires are 25-inch and the front are 22-inch. Why is this?
I thought that on 4x4s you are supposed to put the same tire size on the front and the rear because it causes unecessary wear on the drive system if you don't.

 

most 4x4s have the same gear ratio in both the front and rear axle so the same size tires must be used. However there are a few models such as honda 300 and yours that have differing gear ratios and the makers use different tire sizes to compensate for the difference