Currently fitted to the truck are some nice pattern Trak Grips tyres (which I believe from memory are RF), so good that Barry Ring used them as his pattern tyres for his new run of "Trak Grips". so I'll run with these for the moment and mount any spare in the cargo box. I'm sure I've seen a picture somewhere with the spare wheel on the roof of the cab.
If I were to mount on the tool box then I have to source the tyre holder and that's rarer than rocking horse poo!
Thanks.
Paul