Hi all, will a  WM3 X 18 X 40 rim be ok for a 4 inch trials tyre? I`m sure I used a wm3 on the back of my Matchless but it was a long time ago. Also does the "40" refer to spoke holes? If it does it`s no good for me.

                                         Thanks in advance, Hazel

Yes the 40 refers to number of spokes

WM3 (2.15) is what moden trials bikes use at the rear. In the 1970s WM2 (1.85) were not uncommon. WM1 (1.6) is for the front.

Thank you Carl. I thought that was the case but it`s nice to have it confirmed.