Author Topic: 1934i tyre sizes  (Read 279 times)

0 Members and 1 Guest are viewing this topic.

Offline saluki42

  • Senior Member
  • ***
  • Join Date: Jun 2020
  • Posts: 158
  • Location: Somerset, UK
1934i tyre sizes
« on: 22 Oct 2022 at 10:42 »
Hi ive seen a lot of posts dealing with the 1920s wheel and tyres and was wondering the details for my 1934 Model Z. I have just acquired a couple of wheel and brake assemblies, not too sure what year but definitely the wrong front drum for my Z, the rims are are a plain D section and a rough measure are 20 1/2" diameter. My question really is about what size tyres should I expect to fit and just as importantly is this D section rim period correct for the mid 30s bike or was it more likely to have had a raised centre to the rim.

Chris

Offline cardan

  • Master Member
  • ****
  • Join Date: Jul 2007
  • Posts: 1389
  • Location: Adelaide, South Australia
    • Leon's Vintage Motorcycle Page
Re: 1934i tyre sizes
« Reply #1 on: 22 Oct 2022 at 12:36 »
Hi Chris,

1920s rims are "beaded edge": they have hooks that hold onto a rubber bead on the tyre. The tyres can be stretched onto the rim.

By the 1930s all tyres were "wired on": the rims have a "bead seat" where the bead of the tyre sits. Because there is wire in the bead of the tyre, the tyre won't stretch and the rim needs to be "dropped centre" so that the the tyre can be fitted and removed.

Sounds like the rims you are describing are beaded edge? 20 1/2" probably means they suit 26x3 beaded edge tyres. 26" is (nominally) the outside diameter of the tyre.

Wired-on rims (and tyres) are quoted by rim size rather than outside diameter. Most 1930s rims were 19" ("bead seat diameter" - the ledge where the tyre sits). Then the rim sizes are WM0, WM1, WM2... a WM2 rim takes at 325-19 or 350-19 tyre which is typical for a 1930s bike.

A photo would help.

Leon

[Edit: Should have said that beaded edge rims, universal in the early 1920s, had pretty much disappeared by 1928 - wired-on was a much better plan. Funnily Dunlop had been making wired-on tyres since about 1902!]

Offline Doug

  • Administrator
  • ****
  • Join Date: Mar 2004
  • Posts: 4506
  • Location: Glen Mills, PA, USA
Re: 1934i tyre sizes
« Reply #2 on: 22 Oct 2022 at 14:10 »
Chris,

The 1934-35 heavyweight models used a 19 x WM3 rim. I have the original rims for my 1934 OE1, and (90% sure they are original) for my 1935 OW1.  The tyres for the heavyweights (ohv & sv) were described in the catalog as "26 x 3.5" or 19 x 3.5 in modern parlance.

On the '34, the center well is painted black, with a fat 1/8 blue pinstripe on either side. The '35 rims have been repainted, so cannot say if they carried on the following year. By the time of the Aero models they seem to have switched to a gold pinstripe.

-Doug


Offline saluki42

  • Senior Member
  • ***
  • Join Date: Jun 2020
  • Posts: 158
  • Location: Somerset, UK
Re: 1934i tyre sizes
« Reply #3 on: 23 Oct 2022 at 11:13 »
Thanks Leon, Doug
That gives me all the information I need. The front wheel assembly I'm picking up in a day or two will need stripping anyway so I'll fr rim that and hopefully I'm picking up a rear hub and drum at the same time.

Thanks again
Chris

Offline cardan

  • Master Member
  • ****
  • Join Date: Jul 2007
  • Posts: 1389
  • Location: Adelaide, South Australia
    • Leon's Vintage Motorcycle Page
Re: 1934i tyre sizes
« Reply #4 on: 23 Oct 2022 at 11:18 »
Will you build the new wheels yourself Chris? It's good fun and not too hard.

Leon

Offline saluki42

  • Senior Member
  • ***
  • Join Date: Jun 2020
  • Posts: 158
  • Location: Somerset, UK
Re: 1934i tyre sizes
« Reply #5 on: 23 Oct 2022 at 11:21 »
Never tried it before Leon but is something I've fancied trying so I may have a go and see how far I get.

 

motorcycle