If you are looking for new tires, I think Kenda is the only company making them. Try Google Kenda S7 and see what pops up. Maybe Niagara cycle carries them, they have an on-line catalog. Good luck.
Those are the ones. Incidentally, there are lots of very skinny road tires(<1"; 23mm) for 650c wheels that have the exact same bead-seat diameter-- 571mm. Those would look ridiculous and likely roll off your rims. These Kendas are the right thickness (@1 3/4"; 44mm) and, b/c QBP carries them, you can get a set for about $40 at any bike shop.