My experience with the belts is that they run very long if your pulleys are in good shape and !clean!
I run on one track where 1/5th big scale cars run as well. They have rubber tires and leave a lot of rubber grains (graining
) on the track. If you pick this sticky stuff up and get it on the 16t pulley in front, the belt will strip if you dont remove the nasty stuff quickly.