Back when Michelin became the sole source for tires in MotoGP after 2015, they requested that the series move back to using 17-inch wheels. Now, that change has been approved, and it’s in the rulebook, starting after next season.
Currently, MotoGP racers are running 16.5-inch rims, for a compromise between the stability of a 17-inch rim and the handling of a 16-inch rim. Of course, all sorts of other technical factors come into play as well.
World Superbike already made the move to 17-inch rims as standard for the 2013 season, as part of that series’ move towards relevance to street riders. Michelin’s reasoning behind their request for the change isn’t stated in MotoGP’s press release (below), but it’s likely something similar: They want to sell tires to people with street bikes (that’s the whole point of this endeavor, right?), so they figure it makes sense to play with 17-inch wheels on MotoGP prototypes.
Following the successful tender of Michelin to be the official MotoGP class tyre supplier it was agreed, at the request of Michelin, that the rim size from 2016 will be 17”. This required a change to the regulations which currently specify an exclusive rim size of 16.5”.
Postponement to Implementation of a Technical Regulation
Current regulations require all wheels to be homologated with effect from 2015. In the light of the regulation change above it was considered unfair to require teams to buy new, homologated wheels for 2015 and having to replace them with 17” wheels for 2016. The Commission agreed that the implementation of homologation requirements for the MotoGP class will be postponed until 2016.
The requirement for wheels for Moto3 and Moto 2 machines to be homologated from 2015 remains in place.