Narrow tyres on older 27 inch rims

Pedalitis · Mar 9, 2015

I've just tried fitting some 630 x 25 (27 x 1 inch) Panaracer Pasela tyres to some older but unused Weinmann Alesa rims. They are clincher rims but they don't have the distinctive lip that you find on more modern (even 1970s/80s) ones. At anything above about 70 psi, the tyres come start to come off the rims. The tyres are rated at 115 psi.

Am I right in thinking that these rims are simply too wide for the tyres and I'll need at last 630 x 28 (27 x 1 1/8 inch) tyres?

Has anyone else had this experience?

Thanks
Bob

keithglos · Mar 9, 2015

Re:

You appear to have the original 27 x 1 1/4 which size has nothing to do with tyre width. It was a nominal size, the rim bed for the wire bead was 1 1/4 inches each side less than the overall nominal diameter of the tyre 27 inches. The tyre can be a little more or less than the theoretical diameter, but the measurement assumes the overall diameter to be 27 inches. So the size would always be marked 27 x 1 1/4.

These are not clincher rims but wired-on.

This was a far simpler system which we used in the 1950 / 60s, Apart from junevile the entire UK cycle production used only 4 sizes of tyre. The rare 28 x 1 1/2 and the common 27 x 1 1/4 26 x 1 3/8 26 x 1 1/4. Out of 300 tyres in stock there would be perhaps 4 28 inch.

GasPipeWarrior · Mar 9, 2015

Pedalitis":pwevajt0 said:
I've just tried fitting some 630 x 25 (27 x 1 inch) Panaracer Pasela tyres to some older but unused Weinmann Alesa rims. They are clincher rims but they don't have the distinctive lip that you find on more modern (even 1970s/80s) ones. At anything above about 70 psi, the tyres come start to come off the rims. The tyres are rated at 115 psi.

Am I right in thinking that these rims are simply too wide for the tyres and I'll need at last 630 x 28 (27 x 1 1/8 inch) tyres?

Has anyone else had this experience?

Thanks
Bob

Velobase has the Rim Outer Width for Weinmann Alesa 210 rims as 24mm so maybe too narrow for your Paselas?

Pedalitis · Mar 10, 2015

Re:

Thanks for the replies. As I guessed, wrong tyres for these rims so back to something wider. Always something new to learn!

Wheelnut · Mar 10, 2015

Actually, it is usually okay to use narrow tyres on older rims such as the Alesa. However, you cannot use pressures above about 60psi.

Pedalitis · Mar 11, 2015

thanks for the information. Bob

Apple Tree · Mar 13, 2015

The tyre pressure is the limiting factor here not necessarily the size of tyre. As Wheelnut says, keep it to about 60/65 psi, no more other wise the tyre will blow off. You also are in danger of destroying the rim by pushing the rather weak sides out. Ask me how I know !
Many people are misled by a modern tyre saying it is ok for 100 psi + but as I point out to folk, can your old rims take it ?

Narrow tyres on older 27 inch rims

Pedalitis

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keithglos

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GasPipeWarrior

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Pedalitis

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Wheelnut

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Pedalitis

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Apple Tree

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