AJS & Matchless Owners Club

Hi , I'm looking at replacing the wheels on my G5 ,I've had a look at the rims for the sizes but there are no marks ,apart from a made in England stamp. Any help regarding wheel sizes, spoke lengths and tyre sizes would be greatly appreciated.
Thanks Brian

My model 8 has 18" wheels, tyres are 3.25-18.

Thanks for the info Bill