Re: Since when is 26" now 25"
I just copied off what was on the sidewall.
Trelleborg T-608 37-590 26x1 3/8 Made in Sweden
So the wheel is the English 590 standard. Tires are at least 30 years old from when my great uncle last rode it, but has good tread and a little crazing. I plan to ride on these gently until I find new ones, or maybe respoke some standard rims onto the 3 speed hub. I have have found tires online, but they get expensive with shipping.
I have modified the frame a bit and am converting it to a motor. I will post a photo soon.