Cycling UK Forum

> So, 'cos I own n+1 bikes I often get asked to 'do' the family bikes The latest request is an old ladies 3-speed Raleigh Caprice in need of some TLC
> The fitted tyres (Raleigh Record marked as 26 x 1 3/8th & 37-590 on rims marked 18 x 590) need replacing
> The bike also came with two new White Wall tires also marked as 26 x 1 3/8th BUT then marked 3.5 x 66 CM (and Made in India)
> Now, I know about the ETRTO system and Sheldon Brown's useful article on the topic of strange tyre sizes, but in this instance Sheldon has not been helpful.
> My first thought was that IF the 3.5 x 66 CM ws an ETRTO size, then the tyres would be too big for the rims, but out of curiosity I fitted them anyway.
> The 3.5 x 66 CM tyres went on as tight as the ones coming off did; they sit well down into the (hooked) rims and with 50 PSI in them look, well, absolutely fine
> Before handing back to the intended rider, I'll give them a good road test with some sharp cornering too

QUESTIONS
1. What do you think about these strangely marked (3.5 x 66 CM) tyres and am I able to assume they'll give a safe ride?
2. What other tests and / or measurements could I make to ensure compatibility with the rims?

3.5 x 66cm sounds like (yet another) arcane sizing method, whereby the overall diameter of the mounted tyre is 66cm, and the width is 3.5cm thus making the bead seating diameter 59cm.

Fortunately if the tyre has 26 x 1-3/8" (and only that) writ upon it elsewhere, that is as good an indication as any that you are dealing with a tyre that mounts onto a 590mm rim, and it'll be fine.

Apart from the possible quality issues associated with Indian made tyres; they are often a bit, uh, 'variable'.

cheers

Thanks Brucey - as yo say, just another arcane system

If you're not sure about the quality or fit of the tyres, you can get very cheap tyres in that size like Michelin World Tours or lots of different Schwalbe ones.

http://www.chainreactioncycles.com/mich ... -prod20463