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Internal Rim Widths and Tyre Size


By DudeistPriest - Posted on 04 January 2017

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

Happy New Year to anyone who reads this:)

Just wondering what peoples thoughts are on internal rim widths and tyre size selection?

I'm currently running 2.3" tyres on rims with a 29mm internal width and while I'm generally happy with the setup the tyre profile is quite square (even at low PSI) which makes the tyres feel like they don't grip up straight away when cornering, if that makes sense (could be my crappy riding skills have something to do with it as well).

Cheers

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I am using blunt 35 rims which have an internal width of 30.2 and 3.0" tyres. They do squirm around a bit when running at 10-12psi but when they are at 18-20psi they are awesome.

The profile of this combo tucks the sidewall in nicely which means I have never had a sidewall injury.

It seems logical to look at the tyre profile that it would make a big difference but whenever I sit on my bike and observe, even rounder profiles look pretty flat on the bottom, so I'm not sure the contact patch alters much with wider rims. I think they just offer more support to the tyre to allow lower pressures and more grip without that roll of the rim feeling when landing sideways etc.

Now riding a plus bike (45mm rim, 76mm tyres) I'm convinced low pressure is the key to more grip, and the wide rim large volume tyre thing just allows for lower pressures. I now run out of legs/gears/talent long before I run out of grip at 15psi.

Not sure if the wider rim allows for lower pressures, I can run mine right down to 5psi but rim strikes are a definite at that pressure.

What kind of tyres are you using?

Specialized Purgatory and Butcher 2 Bliss

When I made the switch to carbon on 2 of the bikes I only noticed the improvement with the i30mm rims, not any negatives. A quantum increase in grip, better feel and feedback, stiffer yet a better ride. All positives. Sure, a big part of this would be due to the carbon factor. But the grip and compliance of the tyre would be purely width/volume/psi related one would think.

When I ride the other bikes with their relatively puny, width envy type alloy rims the difference is clear.

It may well be a riding style thing though as I don't mind the back end moving around a bit. In fact I quite like it...who doesn't???

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