The R5k 'R' model has White Enkei brand aluminium rims.
Front is 17" x 3" to take a 110/60/17 tyre. This remained the same on MC21 and MC28 models.
Rear is 18" x 4.5" to take a 150/60/18 tyre.This changed to a 17" x 4.5" rim on the MC21 and 28 models
The R6k 'SP' model has gold coloured magnesium alloy Magtek brand rims of the same size as the 'R' model.
See the attached file for more details.