I run 26x12x12 tires, and run 2nd high..Ive NEVER gotten a motor to carry 3rd high yet...even my big N52M wont..it trys but wont...put a zip tie in the govenor spring to pull the RPMS up...that way you get the full 4000rpms.. RPMS is speed...so if you can hold the RPMS up, that means more speed you will carry...you can actually move as fast with slower speed gears as you can with bigger ones IF ur rpms are up...but change the pulleys to get the desired speed...