It may not be the fault of the bike shop that they do not have stock. It can be very hard to find replacement bikes or parts in today's market. I tried to find a replacement for a front tire on a recumbent bike. The existing tire is a Primo Comet 406 X 1.35 (20") road tire. In past years I could find numerous sources for this tire. Not these days. Came up with no sources that have one in stock. I could buy a Schwalbe overpriced tire that fits at about twice the old price but I absolutely hate that brand with a passion.