Hitchcocks Forum

Hello.

I plan to convert my 350 to Trial version.

What is the tire size recomended for WM4x18 and WM3x18 rims?

Thank you

Le Chevalier Noir in France

Hi Guys ------------ I see that you intend using an 18" rim...Even though this is smaller than the standard 19" one, I would give some thought to changing your swing arm to a trials one...The arms on the road one have an angled approach at their front end which makes any clearances VERY minimal.....Trials tyres by their very nature will have a larger cross-sections so it's always going to be cramped in that area......I know others on here have fitted trials tyres to standard 19" rims..maybe they could offer some "hands-on" advice ??

Chevalier Noir,

Tyre size is an issue with the standard swinging arm, I tried a 4.00" x 18" Avon AM26 rear on my project (WM3 rim) and it would only fit with the wheel at the back end of its adjustment. It might not have helped that Avon's 4.00" actually measured 4.375"!

Any 3.50" or 100/90 section tire will be ok on a WM3 rim, a 410x18 tyre should also fit. A 4.00"x18" tyre might be ok if it really is no wider than 4.00", this might vary between different manufacturers and even different tyres from the same manufacturer. I would be tempted by our host's wider swinging arm I I were fitting any modern big trials tyre.

Are you the same Chevalier Noir I have seen on the French forum?

Regards,

Adrian

thank you four your answers and advise.
Hitchcocks answer me that using WM3 is enough as the maximum tire size will be 400.
I plan to use Pirelli MT43. I will try to measure them before to be sure they do not exess 400.

Yes Adrian, I'm the chevalier noir from french forum!

I found the real with of the Pirelli MT43 I intend to use! It's 4 3/16, meaning 4.19.
(from here : http://www.rickramsey.net/TE610mods.htm#reartrailstire )
Adrian, do you think it will enter?

The MT43 will enter, it's just a question of how far! 4 3/16" = 106.36mm, that's approx 5mm less than the supposed 4.00x18" Avon I first tried. It will be enough to give you a useable chain adjustment range, though you will also need to check clearance with the chain guard. If that is the tyre you really want you could trim the inside of the chaiguard to avoid the tyre rubbing against it.

Regards,

Adrian

Thanks!
I plan to rmove the chain guard, so it should be no problem...