The Mefo 90/90-21 front tread,by design does run backwards.
Check Direction Arrows on sidewall !
The Heidenau K60 90/90-21 front tread, by design runs conventional.
The Mefo tread is slightly softer than Heidenau K60 tread.
DO Not OVER INFLATE.
Size/Load/Speed/Pressure rating is on the sidewall!!!!
A V groove/chevron design front tire tread is designed to hold material.
Where as a drive tire is designed to displace material for better traction.
Case in point-
Mount a chevron type tractor/backhoe/loader tire backwards pulling material into the tire-
The unit won't pull the hat off your head.
Mount a chevron tire directional to displace material from under the tire-
Ride Safe,Have FUN,
Adventure Cycleworks Providing support to the Adventure Touring Motorcyclist in Fairbanks, Alaska