Originally Posted by
Doohickie
This.
When I started riding again in 2008 after 20+ years away from cycling, I had never even heard of 700C tire sizes. If you scoured my early BF posts you'll probably find a few from me asking what the heck a 700 tire is and how it compares with 27". To make it more confusing for me, I also acquired an old Raleigh DL-1 around that time that has 700B tires (aka 28 x 1-1/2).
See also.
Interesting that 27 was so wide spread in US. 700B = 635 is the classic size for utility bikes in Scandinavia. The size is obsolete, so no new bikes are made in that size. But it's still very easy to get new 635 tires here.
I have an almost antique bike, with the largest tire size ever made for safety bikes. 642 mm, a total nightmare to get a new pair. They are probably still made in China. I've seen them in one online shop in Australia.