599 mm tires and 26 x 1.375 Rims
One of the biggest issues with old, American-made roadsters is the fact that many had a now-obsolete rim and tire size, 26 x 1.375. While these tires at first glance seem like regular, 26 x 1 3/8 tires as you would find on millions of English bikes (the Raleigh Sports in particular), this is actually a totally different rim and tire.
26 x 1.375 has a bead seat of 599 mm, whereas the common English size is only 590 mm. The result is that English bike tires won't fit an old, US lightweight with the 599 rims.
One trick is to try to slip Schwinn roadster tires onto the 599 mm rim. These are 26 x 1 3/8 x 1 1/4 and are 597 mm tires. This is very close to 599. However, the fit only works on some wheels. 599 rims with low side walls seem to work best.
Unfortunately, the rims on this bike have relatively high side walls and seem to allow the use of both a coaster brake and caliper rim brakes. The low side wall tires from the period appear to be made only for the coaster brake. The result is that the rims on the Westfield Sports Roadster simply will not allow me to slip the 597 tire over the side wall. I spent over an hour trying various methods to slip the tire on. No luck.
I am not interested in running 70 or 75 year old tires on this bike. Many of these old tires have dry rubber that cracks under stress. Actually, that is a "best case" failure because you can see it coming. The worst case is a tire with a hidden rot in the cotton chords, which then delaminates during a ride without much warning. This is much less common than cracking rubber, but still possible. The bottom line is that I always put fresh rubber on an old bike.
The Basic Durability Test Must be Passed
Every bicycle I re-build needs to be able to withstand what I call the "basic durability test". This test involves the bike being able to withstand a 1 hour ride on pavement of "average local condition" five days per week. This amounts to about 60 miles in a week, if I ride at an average of 12 mph. This is not particularly fast, but taking into account stops at lights and signs, it's what I would call an "average" ride. I just don't think 75 year old tires would hold up under such a test, so I put fresh rubber on all my bikes. This includes tires, tubes, and brake pads (where we have hand brakes).
Time to Source Rims
I now need to source a rim that takes 590 (preferably) or 597 mm tires, but retains a profile very close to the original rims. The spokes for the original rims are just a hair short, even though they are stock and original to the bike. My plan is to source a rim very close to the original profile, but perhaps a hair smaller. This would allow reuse of the original spokes and hubs, but a simple swap of the rims. The idea here is to get as much originality, but allow the use of modern, new tires. I have a couple ideas, which I will pursue this coming week.