Honda SLR / VIGOR / FMX 650 rear tyres

[el vencejo]

Hi, I've stripped down my slr 650, reduced by 29kgs  
Waiting for FMX back wheel to arrive.
I need advice on rear tyres; I've ordered one of these for the front:
http://www.aaa-racing.com/product.php?productid=299&cat=75&page=1
120/60 - 17 ultra-soft rubber.
The matching rear tyres are 165/50 - 17.

¿Will that size fit without fouling the chain?

¿anyone got a spare front hub for an slr/vigor?

Cheers all

[el vencejo]

Thought it was an easy question.   

Done more research, seems that a sticky rear to match will need to be 155/620/17.