Standard procedure to run 16.5 on the front of the motards too. Greater overall diameter than the 17 tyres. Would be so interested in getting some take-offs haha. Doubtful you could keep the heat into it or get any feel with the extra stiffness on a light bike but anyone gonna hook a bloke up?
I'd be shocked if you could get your hands on some take offs. I bet those things come out of a truck, onto a warmer, on to the bike and straight back into a truck never to be seen again.