This just in from the FIM:
FIM Road Racing World Championship Grand Prix Decision of the Grand Prix Commission
The Grand Prix Commission, composed of Messrs. Carmelo Ezpeleta (Dorna, Chairman), Ignacio Verneda (FIM Executive Director, Sport), Herve Poncharal (IRTA) and Takanao Tsubouchi (MSMA) in the presence of Javier Alonso (Dorna) and Mike Trimby (IRTA, Secretary of the meeting), in a meeting held on 14 June 2014 in Montmelo, made the following decisions:
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.