General => Douglas Motorcycles - General Discussion => Topic started by: billowens on 05 Jul 2018 at 08:39

Title: Wheel diameter
Post by: billowens on 05 Jul 2018 at 08:39
I'm getting confused, different forum topics suggest wheel rim diameters and different tyre sizes
I have a 1926 EW Douglas 350cc
What should the rim diameters be and should the drum be laced to one side of the rim
I've posted in wrong area, that's how confused I am!
Title: Re: Wheel diameter
Post by: eddie on 05 Jul 2018 at 09:45
From the 1926 brochure:

  WHEELS.  The wheels are built to accommodate 25" x 3" balloon tyres; the rims will also take the following tyres: 24" by 2¼", 24" by 2½". The heavy steel rims are spoked by means of 40 spokes, tangentially arranged on a new design of hub. The lubrication of the bearings is arranged for by pressure grease gun.  26" by 3" wheels can be fitted at extra cost.

The 1927 brochure states:

  Heavier gauge spokes are fitted than on last year's model, to carry the extra load when taking a pillion passenger.   26" wheels with 700 by 80mm tyres can be fitted for 30/- extra.

  Hope this helps,
Title: Re: Wheel diameter
Post by: Doug on 05 Jul 2018 at 11:07
On the 360EW, the brake drum formed one of the hub spoke flanges. On the heavyweight models, the brake drum was detachable, so the hub had two flanges and all the spokes were laced to the hub. c1930, the 350 models started to acquire the detachable brake drums at the rear and eventually it was phased in at both ends. Of course, over the years, your EW might have acquired wheels from a different year or model.

Title: Re: Wheel diameter
Post by: billowens on 05 Jul 2018 at 12:06
So I guess the 20.5 inch diameter rims are totally incorrect!
Title: Re: Wheel diameter
Post by: eddie on 05 Jul 2018 at 13:12
They may not be!
       The old way of measuring tyres was the overall diameter x width. The more modern way is to measure the rim diameter x the tyre width. The old system also assumed the tyre had the same height as it's cross section.
       The later system is less likely to provide a mismatch of tyre and rim. For example, all 19" tyres will fit on 19" rims but there is a recommended rim width for each width of tyre - the widths used to be classed WM1,WM2,WM3, etc. - nowadays, it is more usual to find the widths quoted in inches (1.85, 2.15, etc) even though the world has now gone metric!

 So the original size tyre (25" x 3") would actually fit on a rim 19" diameter (measured to the bottom of the rim - not the overall diameter of the rim), as would a 24" x 2½" tyre. It would appear that the third option of a 24" x 2¼" tyre would require a rim of slightly larger diameter (19½").

Title: Re: Wheel diameter
Post by: richard s1 on 07 Jul 2018 at 14:32
If your EW still has the original beaded edge rims, then, unless I'm very much mistaken and things have changed recently, it is impossible to get new beaded edge tyres to fit anymore.    I think most EW owners have moved to well base rims now with suitable size wired on tyres.
Title: Re: Wheel diameter
Post by: Alan on 07 Jul 2018 at 23:24
This is what I did on my B29 (picture on this site to show you what this looks like and discussed some years ago on the forum).
These rims are off the shelf and give you a nice choice of new, safe tyres and means you don’t have to trawl lots of swap meets looking for an aged and hopefully not cracked or gone stiff pair of originals.