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The horse is dead but may I beat it one more time?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Onder, May 21, 2018.

  1. Onder

    Onder

    Joined:
    May 11, 2010
    I know the rim size threads have been only exceeded by oil threads but could someone
    actually confirm that a WM4 19 or a WM3 19 can fit the front and back of a 74 850
    that is unchanged from the factory? That is WITHOUT further mods .
    Just measured the WM3 19 on my Trident and compared it to the WM2 19 on
    the Commando and they are almost identical , same TT100 tyres.
     
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  2. kommando

    kommando

    Joined:
    May 7, 2005
    Fullauto is using WM4 front and back and reports good handling. It will change the profile of the tyre but as tyre sizes vary from maker to maker hard rules as to what sizes work do not apply unless confirmed by someone with the same rim width and tyre size fitted.
     
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  3. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Maybe I am bit nit-picky here but FYI, a WM4 rim doesn't actually exist. Sure, there are wide rims out there but they are not WM4.

    -Knut
     
    BrianG likes this.
  4. kommando

    kommando

    Joined:
    May 7, 2005
    I have seen alloy ones sold as WM4, if they are not WM4 what width are they.
     
  5. oldbeezer

    oldbeezer VIP MEMBER

    Joined:
    Nov 2, 2017
    2.5"
    some refer to 2.75" rims as wm5 and so on
     
  6. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    I run WM4 (2.5 inch) x 19 rims with Avon Roadrider 100/90 x 19" at both ends. They will fit (just) if you use button headed cap screws to mount the front guard. They do handle superbly because, wait for it, they are the recommended rim width to get the proper profile. A combination of light steering with excellent stability.
     
  7. JimC

    JimC

    Joined:
    Oct 12, 2007
    Last edited: May 21, 2018
  8. oldbeezer

    oldbeezer VIP MEMBER

    Joined:
    Nov 2, 2017
    according to buchanans a wm5 = 3" I thought it was 2.75. I suspect buchanans knows more than me
     
  9. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Unfortunately, Buchanan is no standardization body. The "WM" designation as used in England ends with WM3, there was never anything larger. I believe the "WM" designation was invented by Dunlop.
    Since then, there is a new standardization scheme called the MT series which is built upon metric sized tyres. So, Buchanan should have used the designation MT w.dd x D instead.
    Here is the appropriate table:
    https://www.maxxis.co.uk/know-your-tyres/motorcycle-tyre-safety/wheels-and-rims

    -Knut
     
    Last edited: May 21, 2018
  10. JimC

    JimC

    Joined:
    Oct 12, 2007

    Nor is Maxxis a standardization body. Since this is a worldwide forum, standards may vary per country. I’ll guarantee you more people are familiar with WM4 than MT2.5.
     
    Last edited: May 21, 2018
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  11. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    With all respect, your statement is rubbish. A generally accepted standard is valid world-wide - how could countries trade otherwise?
    FYI, I was referring to the table to clarify matters. The valid standard is ISO 4249-3:2010 (6th ed.): Motorcycle tyres and rims (Code-designated series) — Part 3: Rims

    This standard is valid in the US as well - like it or not!

    And - btw - the cylindrical bead seat (to which the old WM patterns belong) and the MT rim scross-ections have similarities at the shoulders but are not identical, the MT series being designed for tubeless tires.

    -Knut
     
    Last edited: May 22, 2018
  12. JimC

    JimC

    Joined:
    Oct 12, 2007

    Speaking of rubbish. Evidently you are unaware measurement standards vary by country. ISO vs. SAE. Whitworth vs. US.
     
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  13. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    I don't understand why you quote ancient and off-topic standards. Dimensional compliance is specified in the ISO standard which I cited.
    When you buy a new rim today, it has to be manufactured according to this ISO standard, otherwise it's a one-off and should be sold as such, in which case suitability for off-the-shelf tyres cannot be warranted.

    -Knut
     
  14. JimC

    JimC

    Joined:
    Oct 12, 2007

    You go ahead and run MT whatever rim, I’ll continue with a WM4. BTW, if you want to order a 2.5” rim from Buchanan’s order a WM4.
     
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  15. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    JimC, please be my guest. If you trust Buchanan with your life - good for you. For the rest of us - buyer beware! Please order your rims according to a generally accepted standard to make sure the tyre really fits the rim.

    I rest my case.

    -Knut
     
  16. JimC

    JimC

    Joined:
    Oct 12, 2007

    You didn’t have a case to begin with.
     
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  17. Onder

    Onder

    Joined:
    May 11, 2010
    Oh dear, what have I done...another tyre thread ... mea culpa...but thanks for the info!
     
  18. JimC

    JimC

    Joined:
    Oct 12, 2007
    Throw all your WM4 rims away. According to our resident rim expert, mdt-son, they may be unsafe and don't exist anyway.
     
    xbacksideslider likes this.
  19. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    My WM4 rims are made by Morad in Spain.
    Stamped " MORAD SPAIN 2.50 X 19 40TC 5/11 E DOT "
    Thomas
     
  20. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    For years I ran a 2.50"x18" Akront rear alloy rim on my Norton race bike (with tubeless Avon race tires fitted with tubes). At the time (late '70s?) it was referred to in catalogs as a WM4, but the markings on the rim are "AKRONT 18"-2.50-40-S-393 E DOT SPAIN". The only alloy rim I have that is marked as WM is an old Borrani that reads "BORRANI-WM 3-19-RECORD RM01/4402. I have seen original Smith steel rims on Nortons marked as WM2. I have a 17" SUN alloy rim that was used on the rear of the JS monoshock Norton that is clearly an MT tubeless profile, but is marked DOT T 2.750 17. The original WM specs might only go to WM3 but in the years since many manufacturers have produced rims with the WM profile in wider widths, and the terms (WM4, WM4.5, WM5, etc.) were widely accepted to describe them. If the rims Buchanan's are describing have the WM profile, not the newer MT, it would be incorrect to identify them as "MT w.dd x D". If they have the MT profile, then it would be correct to so specify them. I couldn't find any info on Buchanan's web site that specified what profile their alloy rims (Borrani, Akront, DID, Excell) are. Kenny Buchanan told me a while back that the Borranis are being made using the original tooling, so I wouldn't be surprised if they are still WM profile.

    Knut, I haven't been able to find a publicly available copy of the current ISO spec you referred to (ISO 6054-2:1990(en): Motorcycle tyres and rims (Code-designated series) — Diameter codes 4 to 12 — Part 2: Rims), and I'm not willing to pay for one just to satisfy my curiosity. If you have a copy, could you tell me whether it even includes the old WM profile? I'm guessing it only includes MT and other modern profiles, but it would be nice to know for sure.

    I'm finding it hard to pin down the details, but it seems like ISO standards for motorcycle rims were either not yet developed, or not widely accepted during the period of Commando production. Prior to the ISO standards, most of the alloy rims seem to have been made to some sort of DOT standards. All the rims I've mentioned above were made prior to 1990. Does anyone know when the US adopted ISO standards for motorcycle wheels?

    Ken
     
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