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



## 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)."


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## GTs58

I've seen where some Schwinn literature uses the size 1.75 for the middleweight tire size. I'll bet this is where some of the confusion begins. 

http://www.trfindley.com/flschwinn_1951_1960/1955_04.html


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## Jerry Blais

In math 1.75 equals 1&3/4 but with bike tires there is a difference.  I've always believed that an American made Schwinn bike was the best and Schwinn used tires with fractions (1&3/4 for middleweights, etc.) so Schwinn bikes are a "fraction" better.  It's a gentle reminder for me.


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## 64 Pete

That reminds me......
Should a 26 x 1.75 tired middleweight bike have a narrower rim than a heavyweight with 2.125 width tires?

Thanks

Pete


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## mickeyc

WOW...thanks for the explanations gents, appreciate it.

Mike


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## farkasthegoalie

I recently had a set of BF Goodrich Silvertowns that were sized 26x1.75, fits s7 rim.
may have been one of the first "aftermarket' s7 tires?


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## Saving Tempest

That isn't the hardest part, it's the axle/hub width. I guess I'll go measure my Hornet.


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## Saving Tempest

Are a pair of rims for a DX going to work for my Rollfast ballooner is what I'm trying to figure out?  The front seems spot on but the rear may be too wide for it. Otherwise the rims are new with Kenda whiltewalls and it's a great price.


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## Saving Tempest

And Schwinn middleweights could use 1.95 and 2.125" dia. tires. At least the later ones I've owned from the 90s.


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## Saving Tempest

I have a New Departure brake hub on that Hawthorne/Rollfast wheelset and it looks like the same hub I saw on an S-2...the AXLE is the same, isn't it?

Go ahead and move this if you wish but I don't understand this part of the Schwinn equation.


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## rustjunkie

The spacing should be the same.

https://www.sheldonbrown.com/frame-spacing.html


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## Saving Tempest

*Let's do it! - Tone Loc*


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## Saving Tempest

PS DID it...In time for Christmas.


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## Streetcustom82

Wat is the diff between an original Schwinn tire and a repro? Please lmk thanks


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## rhenning

The manufacturer and the cost to the restorer.   What size are you looking for.  Roger


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## Siestabikes

so is a Schwinn 26 x 1.75 tire 571 ETRTO?


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## rhenning

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


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## Saving Tempest

Siestabikes said:


> so is a Schwinn 26 x 1.75 tire 571 ETRTO?




I've used all manner of 1.75-1.95" from the bike shop or dept. stores that sell tires and tubes. I'm not sure I've ever seen the rims mentioned.

You aren't dealing with this situation for at least the last 45 years anyway, that I can recall.


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## Saving Tempest

My mom would put Schwinns and Huffys together for me from a bicycle junkyard and I used to be able to deal with changing tires and tubes much better before I injured my hand.


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## Brutuskend

BTW they also make a 26 x 2 x 1/34  that will fit a Schwinn S-7. Same ISO but closer in width to a 26 X 2.125


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## Brutuskend

Siestabikes said:


> 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.


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## Brutuskend

rhenning said:


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



yes


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## videoranger

you might like this article:

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


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## 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.


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## GenuineRides

This explains the sizes well.


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## PD Monkey

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


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## GTs58

PD Monkey said:


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



Either one, marked 1.75 or 1 3/4


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