New tyres for my 72 Commando

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It is a pain, as the trade body ETRTO 'recommends that' the rim width is not less than half the fitted width of the tyre.
Hopefully we will get better fitments in the future, the radial should easily deliver that. None of the usual fitments are poor, and have been fitted to rims various over a good many years.
Maybe when Avon get the tyre widths to fit the tyre description it should allow more rim alternatives. I have just noticed that according to Avon the 100/90 - 19 is actually 109mm wide! As well as a 3. 25'' Roadrider, that has universal fitment and higher load index than the 90/90 - 19 front fitment, why list two tyres relatively close in size.
 
There seems to be a lot of discussion about what tire fits on what rim width the best. I have yet to see anyone question the fact that technically AM 26’s are recommended to be fitted on MT rims and not WM’s and how that fits into the equation. I don’t know enough about the entire situation but my gut feeling is that for the average street rider it is a moot point and just a matter of personal choice. FWIW
 
Fullauto said:
Tell us what you found, Tom. Please.
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It's pretty primitive which involves the use of a tracing profile gauge sold at Lee Valley tools to trace moldings in wood working. I did this on this forum years ago (can't find it) but comparing a super venom to am 26 RR. But to keep apples to apples, I did other profiles using the road rider tires and between the two rim sizes. One thing I did notice is the WM2 makes a larger rolling O.D. so you sit taller. Hence when I did a 1430 mile road trip with my mates this past August my GPS recorded 1410 miles total trip mileage compared to what my odometer recorded. I can do another profile picture but I can't find my 1/4 inch graph paper but I would like to do it when I change my front to a new skin. Edited: I had my mileage reversed between GPS and clock. 1410 on gps and 1430 on the odometer.
Cheers
Tom
 
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Fast Eddie said:
Well, as you’ve said before Ash, Avon do now seem to say that this tyre is acceptable on a wm2 rim.

But they also say that the recommended width is a 2.5” rim. So, that’s clearly the rim that they think works best.

They have not amended their web site yet, it still says the min width is 2.15” which is a wm3.
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Not "the rim that they think works best". It is what Avon MAKE the tyre to fit and give the correct profile. If you look at a AM26 100/90 x 19 on a 1.85" rim you will notice one very important thing. That thing is that no matter how hard you lean, you will NEVER get close to the edge of the tyre because of the mushroom shape of the treaded portion. Not an opinion, or conjecture, or "I would think", but what I like to call a "fact". I know you understand this, Nige, but I have been treated as a heretic over this fact for years by others. This means that your 100/90 becomes a 90/85 or something similar when fitted to a 1.85" rim. If you fit the tyre to a 2.75" rim, this will flatten the profile and you can perhaps run off the edge of the tread. It is amazing that they work so well on a rim two sizes smaller than it was designed for.
 
Fullauto said:
Probably because you are runnning the Avons on the wrong rims. The fact that Avon now recommend the 100/90 Road Riders for the 2.15" rims seems like a bit of belated marketing wank. Put them on the correct width rims and they are a different tyre, Superlative.
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So, just to be clear, the Avon 100/90 19 roadriders belong on the MT 2.50 rim ( not sure what MT stands for).
 
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