Belt sizes are a pain in the ---. They never match up. Even the "official" charts vary. I just posted up in Blues thread on belts how to size one up correctly. The 2 main points are: The belt must be at the top of the rear pulleys, and it must sit tight on the drive boss when stationary. Longer/shorter, and you lose potential gear range. Kevlar belts, are softer rubber, and grip better but wear thin quicker. Poly.belts wear longer but stretch over time. Kevlar should only be used in Hi Perf. scoots as they are inspected more often. Poly belts are better in stock scoots as they last longer overall
