Not completely an isolated incident regarding the belt rubbing the back tyre....ours got pretty bad (ie noisy) during our 1250 mile July trip in Spain/France....was sorted under warranty with new belt/pulley/tyre etc when the bevel box was changed....has since been fine. Our 3W is around #92 and was built in April.
If you look closely, the belt is located by flanges on one side of the drive pulley and the opposite side of the driven pulley. On the driven pulley the flange is on the tyre side but the belt will touch the tyre before it can get to the flange. I suspect it is kept away from the tyre by fine adjustment of the bevel box alignment.
