Gates snowmobile belts are built differently from most of the belts available today. We build our belts inverted ("inside out" on precisely machined mandrels) to assure that the tensile cord is carefully and accurately placed in the belt. When the belts are profiled and turned "right side out," they have a slightly different outside circumference (OC).
In addition, the fitting of a belt to an application is very complex. Variables such as angle, top width, inside circumference (IC) and OC can all be varied to achieve the proper fit. Each vendor has its own way to optimize the fit of its belt on the application. The only way to verify that the belt fits correctly is to install it on the drive and operate it over the full speed range.