Rear tyre diameter

Hi,

Could someone please tell me the finished outside tyre diameter for an 18 inch wm2 rear wheel fitted with a Dunlop KR825 tyre ?

Its the outside diameter of the tyre when fitted to the wheel and inflated, that I need !!

I am building the rear sub-frame and want to be able to run the exhaust directly under the seat to keep the bike VERY narrow, but dont want to have the seat too high !!

Thanks to everyone who has kindly helped with tech. advice - much appreciated.

Hi Jon
600mm dia but dont forget the tyre will grow 90mm wide
Robbie PS check your email