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Tyre and rim width compatability

by pcaley
Sun, Mar 13, 2016 21:24
6

I am considering buying some Superstar Components Ultra wide wheels, which have a rim internal width of 19mm. I plan to use 25mm tyres, but a see that both Continental and Schwalbe list the narrowest width tyre for a 19mm wide rim as 28mm. The widest rim they recommend for a 25mm tyre is 17mm. Has anyone used 19mm wide rims for 25mm tyres? Any issues? I am lightweight at only 65kg!

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6 comments

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Vejnemojnen | 6 years ago
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you can even choose 23mm tyres. Those will spread out to cc. 27mm on wide rims.

 

IMHO, anything wider than 25mm on a 19c rim is not optimal for handling and cornering

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mikesm08 | 6 years ago
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COOL, do you guys think then 25mm clincher will be just fine on this rim?
Anyone know if I could squeese it into my cannondale supersixevo 2014, 52cm?
It might just, according to  Frankierae's pic

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chrislee99777 | 8 years ago
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it is ok

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frankierae | 8 years ago
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Hi, completely agree with Dave about the compatibility of 25mm tyres on larger internal rim widths.

I've always considered the ETRTO recommendations baffling. Imagine how unstable cornering a 37mm tyre would be on a 17C rim (a recommended pairing), whilst  a 23mm tyre doesn't even make the cut! 23mm on 17C is a very common pairing when buying a new bike. Cervélo S5, anyone?

I'm a 95kg Clydesdale and recently upgraded from Fulcrum Racing Zeroes (15C) to HED Ardennes+ (20C) for exactly that extra width and tyre volume. I use 25mm Conti GP4000S and they were decidedly light bulb shaped on the Zeroes. Squirmed around a lot at 85PSI (my preferred pressure for comfort, since the rims themselves are rock hard).

Now on the Ardennes+ the tyres have super straight sidewalls. I've settled on 70PSI after a few months of trying and find it to be really comfortable, yet less squishy while cornering. There's less of a whirring noise while riding too, which I suspect means less deformation. Certainly the setup feels faster (however I won't offer that assumption). A sidewall aligned with the direction of load will support the load better of course.

I actually feel that 20C is perfect for a 25mm tyre

The only downsides I've found are a) the tyres are so wide now I have about 1mm clearance from the chainstays (frame dependent ofc), and b) the Ultegra brake calipers only just open far enough for the rims and I get the slightest bit of brake rub. Currently waiting for a bit of wear to make more room 1

Hope that helps!

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pcaley | 8 years ago
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OK - thanks for that I now understand why they are all saying the same thing. I must admit I had not anticipated that an ISO standard would recommend tyre sizes for given rim widths.

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dave atkinson | 8 years ago
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they're correct in that ISO 5575 covers rim and tyre combinations and in theory a 28mm tyre should be the minimum for a 19mm internal width rim:

https://en.wikipedia.org/wiki/ISO_5775

having said that, i've used 25mm tyres on 19mm and 21mm internal width rims for thousands of miles with no issues at all, and i'm 91kg. so i don't personally think it's much of an issue

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