It can be such a lottery at the same shop too, dpepends who serves you.

Went into one of my local stores at the weekend looking for some low profile 27" tyres. Asked the lass behind the counter, she had a brief poke about and came back "No we don't have anything like that."

As I was leaving, a guy who had been fiddling with the window display asked what I'd been looking for. I told him. "How low a profile do you need?". I said it was for a bike designed to take 700C wheels that I'd fitted an old 27" wheelset to which had swallow tyres on that fit fine but the Michelins citys I got foul the frame.

"Oh right, I've got just what you need." Disappeared into the same room as the lass had been in and came back with a couple of Schwable 27 x 1 1/4 tyres which are nearly a carbon copy of the old swallow ones.

Sold them to me and said if they don't fit, as long as they aren't marked, he has some 1 1/8" ones too that he'd be happy to swap them for (they fit fine).

The same lass had previously sold me a 3/32" track cog which turned out to be a 1/8". I wonder how much business she costs them.