The tires for the Schwinn New World have arrived. I decided on the basic Kenda 37-597 black wall tires.
For those unfamiliar, bicycle tires come in an array of sizes. Most tires are marked either in inches or as 700c (or similar). For example, you might see a tire 26 x 1 3/8, or you might see a tire 700c x 40, etc.
However, there is another way to measure tires: by ISO designation. This has quickly become my favorite way of measuring tires. Why is that? The reason is that tires marked using the other systems may be marked the same size, but actually be entirely different tires.
The Schwinn New Worlds are a prime example. The tires on the bike say "26 x 1 3/8". However, not all 26 x 1 3/8 tires are the same. There is 26 x 1 3/8 (ISO 590) and there is the 26 x 1 3/8 that is ISO 597. That 7 makes all the difference. While both tires are marked the same on the wall in terms of inches, you can't mix and match them. In this case, the Schwinn New World should take 597 sized tires, which is a special Schwinn proprietary size. If I were to buy a tire made for an English Raleigh, it would not fit this bike even if they happen to say the same in inches.
That is precisely why I've come to ISO. Tires that are nominally the same in inches are called by true, unique designations. You would see a 590 for the Raleigh size and a 597 for the Schwinn size. That makes it somewhat plain that the two are different tires.
More here from Sheldon Brown:
Fortunately the inner tubes should be the same set.
The market for Schwinn tires is tougher than that for English type roadsters, like my Raleigh Dawn Tourist or Sports. English sized tires seem to be in every corner bike shop, but the Schwinn ones are not. I ordered my Schwinn's from a shop in Maryland. You can also get them on Ebay and on Amazon.