Schwinn Tire Sizes, AKA 1 3/4 does not = 1.75...and more

[Brutuskend]

so is a Schwinn 26 x 1.75 tire 571 ETRTO?

No, All schwinn tires except for one's that fit S-2 rims use factional tires instead of decimal maked tires.
For instance S-5 and S-6 rims use a 26 X 1 3/8 tire with a 597 ISO Schwinn S-7 wheels use a 26 X 1 3/4 tire or a 26 X 2 X 1 3/4 tire both of which use a 571 ISO. BTW No matter what the Basic rim size with Schwinn rims (16-20-24-26) they make S-5 & 6 S-7 and S-2 so a 16 inch Schwinn rim marked S-7 would use a 16 X 1 3/4 tire and so on. Of all the Schwinn rims the only one's that use like size tires are S-5 & S-6 which use the same size tires, namely 1 3/8 tires.
Schwinn may have used some bikes after they stopped building them in Ill. that used 26 X 1.75 tires but those wheels wouldn't have been marked with a Schwinn tubular S - what ever mark.
BTW any rim that will take a 26 X 1.75 tire or 26 X 1.95 tire or ANY modern 26 inch tire can use a 26 X 2.125. You can safely go up and down on the width which is the later part of the tire size (1.75 - 1.95 etc..) as long as you have the clearance on your frame . 559 is the new standard for all 26 inch wheels. The only exception is any older narrow 26 inch tire like Raleigh or other european bikes.

 

[Brutuskend]

Should be a 559 ETRTO tire and would fit on a 26 inch S-2 or 26 inch mountain bike sized rim. Roger

yes

 

[videoranger]

you might like this article:

https://bike.bikegremlin.com/285/bicycle-tyre-dimensions/

 

[Ernbar]

Well I’m having a heck of a time finding a tire that will properly seat in the rims of my 1980 Schwinn Suburban having a tire size of 17x1 1/4. I contacted a Schwinn seller on eBay up in NY and he advertises tires that fit these older bikes. He told me there is no magical tire just the standard 27x1 1/4 size but the problem is getting them to properly seat on these chromed steel rims.
I tried the massaging, inflating, talking and soap lubrication tricks and still get one low spot.
I tried some Kendra’s that I have on my 74 Le Tour on the Suburban and they got pretty close to a good fit. Swapped them back on the Le Tour and they mounted up perfect.

 

[GenuineRides]

This explains the sizes well.

 

[PD Monkey]

This might be dumb, but is it a standard 26 x 1.75 tube??

 

[GTs58]

This might be dumb, but is it a standard 26 x 1.75 tube??

Either one, marked 1.75 or 1 3/4

 

[Danny Anson]

Bought 26" tire and they won't fit on my 26" typhon rims?

 

[rustjunkie]

Schwinn used some odd tire sizes. The most common we see are the 26 x 1 3/8" and 26 x 1 3/4".
Fitting a tire to a rim is all about "bead diameter" which is printed on most tires.
Below are links explaining it:

http://www.sheldonbrown.com/tire-sizing.html

https://www.sheldonbrown.com/rim-sizing.html

From http://www.sheldonbrown.com/chicago-schwinns.html

"In general, U. S.-made Schwinns take oddball Schwinn size tires, with the exception of 630 mm/27 inch, which is standard.

Good mathematics doesn't always help you when it comes to bicycle tires. For example, most "middleweight" Schwinns take 26 x 1 3/4 tires, which are hard to find, not 26 x 1.75 as used on other brands. You might think that these are the same, but they are not.

The 26 x 1.75 size is the normal I.S.O. 559 mm size used on most mountain bikes; the 26 x 1 3/4 (I.S.O. 571 mm) is not interchangeable with any normal tire of similar width, although its bead circumference is the same as the "650C" size used on some high performance 26" wheel bicycles.

Designating the width with a fraction instead of a decimal usually signifies a straight-sided rim, not a hook-edge rim. The rim/tire diameter is also slightly different. Let the tire buyer beware! There are similar problems with other Schwinn tire sizes. The most common difficulty is that the Schwinn 26 x 1 3/8 (I. S.O. 597 mm) interchanges with the British 26 x 1 1/4, not the British 26 x 1 3/8 (I. S.O. 590 mm)."

pretty much everything u need to know

 

[Danny Anson]

Found an old tire in the pile says 26" x 2x 1 3/4. It fits. But the 2x 1.75 doesn't.?