i have a Michelin AC10 on the rear and the part catalogs note that you can flip the tire to go the reverse direction of rotation when the little "M"s in the knobbies where off. mine are getting there and im wondering if this is really necessary. the ***** appear to wear even and i dont see how flipping it around will give you longer tread life....any suggestions?

 

It's all about grip. If your not an aggresive rider you won't notice a big difference.
The leading edge of the ***** gets rounded off and you lose some grip. By turning the tire around you you put the trailing edge forward and get some grip back. Not a lot though since a good portion of the **** height is now gone. We're all different so you make the call for yourself.

 

its more to get more traction. if your do a lot of road riding, you might not need it, but i seam to round off the *****, so it helps me get more usable life.