Purpose of 18" wheel?

[BPJNT]

For off road purposes, what is the real purpose or added benefit of the 18" vs the 19" rear tire?

Thanks :)

 

[John Harris]

Common knowlege is that OD (rubber on the ground) of the 18" and 19" tires are about the same. The difference in the tires is therefore the sidewalls ie the 18" has deeper sidewalls. Motocrossers like the 19" tires because the narrower sidewalls do not deform as much under hard cornering or side stresses, if you prefer. Woods riders like the 18" tires with the high profiles and deep sidewalls to help cushion the rims from damage from rocks, etc.