I have come by a pair of Continental Podiums (tubulars) 27 " , the seller told me they are the same as 700c . Even though they are marked 27" I'm sure they are 26" - 650c something like that , I'm not at all familiar with 650's , I thought if anything they would be to big , I have a 700c tubular and I laid it on top of the Conti ,and the difference was clear . . There is a lot of info on Sheldon's site , the first thing they say is there is a lot of confusion out there about 27"s but most of it is about older tires . My tires aren't that old . So question , what have I got ? Thanks , Mark .

What does the lettering on the tire itself say?

Hi @ HillRider , the lettering on the tire says Continental Podium 27" 19mm . Thanks .

Are you sure that there isn't a number like 622 x 19 or similar? 622 is the ERTRO size for 700c. 630 x 19 would be 27"
https://www.sheldonbrown.com/tire-sizing.html#iso

Sew ups are well known for not being of any final "size" until mounted. The casing has a large amount of stretch and can often seem smaller in what might be the final size then what is the reality.

Years ago we were clearing out the adjacent to the bike shop house (had been used as satellite storage and work space for years prior) for it's becoming a residential rental again. I came across a couple of orange Clement sew up tires. They were smaller than a 590 ISO tire's bead diameter when lightly inflated. I questioned their size and the boss said they were the usual "700" size. Sure enough I dry mounted them on a pair of rims and they fit (although tight) and inflated to the usual shape. BTW I was also told to not ride them in the rain. I glued them up and had a few weeks of heaven, the nicest tires I can remember riding.

I suggest test mounting. Andy

OK Andy, I will try mounting them , but like I said they are clearly smaller than 700c . [MENTION=205349]dsbrantjr[/MENTION] thanks for the thought but the only thing that states size is what I have already posted .

This should help-
https://www.probikekit.co.uk/blog/ar...ubular-sizing/

as you pump them up, mounted on the rim, they get smaller and press the wet glue out..



700C/622 bead seat, wheels is a made to be usable on bikes with glued to the rim race sew up tires on them..

some are marked 28" ....







...

Tubular tires don't have a bead, so they don't generally (ever?) have a bead seat diameter listed... although places that sell them will sometimes give it as an equivalence guide.

Continental does make 650c size tubulars, and they label them 26".

This kind of questions pops up in here every few months with the OP sure they have something other than regular 700c equivalent size, but they don't.
700c tubulars fit just fine on 700c clincher rims, so if you have a spare wheel around you can prove it to yourself.