Here's a pair (2 tires) of new old stock 24" x 1.75" Schwinn Spitfire tires. Will also fit a larger 2.125" rim.  Will not fit Schwinn S7 rims. ISO 507.

These tires are from the 1970's. Have been stored in a climate controlled warehouse. Nice and supple without any cracking. Some are dirtier/dustier than others depending on where they were on the pile, but all new old stock.

Shipping to run $13.00 in the USA, $80.00 internationally.