I just got these brand-new, never-touched CONTINENTAL HIGH PERFORMANCE road tires and went to install them on my bike when realized they seemed just a bit to small for my 27x 1 1/4" rim, so I checked the description size on my new tires and came across a new size I've never dealt with before continental 23-571(650x23c)

My question: can I use these tires on my most recent project? And if so what other info to know about doing this switch?


2 Answers 2


No. A 27 inch tire has a 630 mm bead seat diameter, 650c has a 571 mm bead seat diameter. That means the wire/kevlar bead of the tires has a diameter of 571 mm, and the inside of the rim has a diameter of 630 mm. The bead of the tire is designed to have very little stretch (so it stays on the rim at high pressure), so there is no way that you could fit 650c tires on a 27 inch wheel.

(also, see Can I put 700c tires on rims made for 27 x 1.25"? for a case where you might be able to squeeze smaller tires on a larger rim—but definitely shouldn't.)


There is essentially a half inch difference in size. And tyres are often hard enough to get on a rim that's the right size. So unless you're Mr Incredible/equally strong and are willing to risk your tyre breaking.... Sorry

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