In what scenario would someone use a 16.5" front, or rear, wheel? What are the benefits of using this size wheel/tire combo? If you use a 16.5" front does that dictate the use of a 16.5" rear? Is this wheel size street-able?
A 16.5" wheel gives a larger contact patch at higher lean angles. On the road you would rarely be able to achieve such angles and on track, unless your running respectable superstock times at a minimum, you would unlikely benefit. The other issue, unless I'm wrong, is that you will not be able to find a DOT approved tyre to fit and the latest generation of 16.5" slick tyres are very expensive to say the least. You would be better off sticking to a 17" specification wheel and fitting a track tyre such as a Bridgestone R10 for example.
It's also interesting to note that the rules governing the use of 16.5" wheels in WSBK has now changed. From next season all teams will have to run 17" wheels in line with the production models they are based on. You will likely see the 16.5" wheel phased out entirely with the exception of its use in MotoGP.