650A is also called (IIRC) 26x1-3/8 (590mm BSD) and this was a very common size up until the early/mid eighties. The 26x1-3/8 was the common name for the size - I didn't even realize it was also called 650A until a few years ago, and I owned, serviced, and sold tires for many '650A' bikes over the years.