So I bought two Kenda K40 26-1 3/8 (590-37) tires from Canadian Tire for my old Schwinn 1990 Mirada since I gave my two Schwalbe Marathon Plus to my wife for her Mirada. I wanted to use my old bike when we ride together. Turns out, they are way too big. Why two different 26" sizes (559 and 590)?!?

I ended up buying two Schwalbe Marathon 26" (559-40) touring tires from ChainReactionCylce instead.

There are quite a few more than two sizes of 26" tires.

See the Sheldon Brown site.
https://www.sheldonbrown.com/tire-sizing.html

Initially the tires were essentially sized by the outer tire diameter. So, a 26x1 tire and a 26x2 tire would have about the same outer dimension which required different rim sizes. Plus tires and wheels were made around the world, with each manufacturer doing things a little different. But it became a mess until a few rim sizes were mostly standardized.

Then what was done was putting larger tires on the mid-sized rims (650b), so they really aren't 26" anymore.

Anyway, there is greater standardization now, but the vintage bikes will remain in use for quite some time and one just has to pay attention.

As noted there are more than two "26 inch" bicycle tires and there are at least two "20 inch" bike tires (ISO 406 and ISO 451). Bike tires sizing is a study all of it's own.

Why make things simple when you can make them complicated...

Thanks

27 > 28 = 29 > 27.5

¯\_(ツ)_/¯

the tires you bought are for a schwinn, more than likely... the bead area is different, too.

The FRACTIONAL size is a dead givaway that it's most likely a Schwinn specific tire... MTB and japanese cruisers use a DECIMAL sizing mark on the tire width... 1.75, 2.125, etc... 1 3/8", 2 1/4", etc., usually means it's Schwinn specific... and the bead will be nearly flat shaped, instead of a more normal bead shape(rounded outwards).

and to complete the informing, the "26 inch" dimension refers to the overall height of an about 1.95" tire, when inflated on the rim... not the rim's diameter. A "26 inch" MTB/cruiser rim is actually about 22.675" diameter...

Absolutely!

I'm a fan of referring to tires by their ISO sizes. IE, the 40-559 tires you bought. 40mm wide, 559mm rim (bead seat diameter). I think that's GENERALLY a less confusing system. Trouble is, few people outside the biking community know what the heck a 559mm tire is.

"What is that, European?"

Just so happens the bike is a 1991 Schwinn. That's why I thought it was ok, until I tried to install them and there was a few centimeter gap between the rim and the tire...

Anyone who knows anything about bikes always goes by the ISO size.

and that "schwinn" was made in Taiwan, not the USA, i'd think...

it's a world standard "26 inch" rim.... not a Schwinn rim. you'll need to get tires that conform to a non-Schwinn standard.... and have normal beads that actually hook into the rim bead area, too.

the schwinn "fractional" labeled tires will blow right off the rim, probably... or not fit in the first place... which is what brought you to this forum with your issue.

by 1991, most Schwinns were already being made in Taiwan, to World standards. Schwinn fell victim to their want to NOT CHANGE, during the 80's... only the highest end schwinns were still made in the USA, and they were also switching over to world standards, and built with world sourced parts from various countries... "Schwinn approved" markings eventually disappeared from the derailleurs, brakes, etc., on the entire line of bikes....... the bikes became lighter, and much less expensive to maintain.

i have a mix Schwinn here right now... it has the heavy, small tubing frame, with a tiny, heavy seat post... and SHIMANO SIS derailleur and Shimano cantilever brakes, too.... it was already too late by then... the company collapsed, and the company's name was bought up.... Schwinn's famous name continues to help sell bikes to this day....

most of their Schwinn only franchised shops folded during the 80's... i have about a dozen 22(yep, ANOTHER tire size!) inch tires here from one of those shops... got them for free... and haven't sold a single one yet... pretty sure that Schwinn was the ONLY manufacturer to ever sell bikes with 22 inch tires... oops, huh?
they zigged when they shoulda zagged.

590 wheels were used by TONS of bike brands.

597 is a more Schwinn-specific size in that neighborhood, although it was also used by some other brands.

590's... old 3 speeds mostly...

i have a "schwinn" here with "schwinn Cruiser classic" tires on it... no ISO numbers to be found... the rim measures 22.675 dia.... the bike is a mix of schwinn-like steel, and shimano bits.

the raleigh limited 3 sp. has 590's on it, the rim dia. is 24 inches even. No ISO numbers showing on the tires or rims...

and the old three speed someone gave me has "Million" brand tires(no ISO# showing), a sturmey archer 3 sp.hub, and rim dia. is 23.75... the previous owner said the bike is a Murray...

both 3 speeds have tires labeled as 26 x 1 3/8"... the "schwinn" has 26 x 2.125" on the tires... i'll assume they are beaded tires, not schwinn type... since the rims are standard MTB diameter... tread is rectangle checkerboard pattern, much like schwinns of old.... sigh.

and if i dig thru the boneyard, i might find a couple other "26 inch" rim sizes out there.....

no wonder the OP ended up with the wrong tires.....

26" tires have/still refer to the following rim bead seat diameters (BSD): 559, 571, 584, 587, 590, 597, 599. 559 and 590 are still sold on new bikes around the world. 590 is not so common in the USA.

As noted above, going with BSD, like motor vehicle tires and rims, is far less confusing.

What I will say is that the OP isn't alone. In fact there was another thread that showed up at almost the same time.

https://www.bikeforums.net/bicycle-me...n-t-equal.html

I would venture to say that many of us who work on our own bikes, and the occasional neighbor bike has mixed up either 26" sizes, or 700c/27" sizes at one time in our lives. At least now there is a plethora of information on the internet.

There are also several different 24" tire sizes including 507, 520, 540, 541 (600A), 547.

My first "road bike" when I was a kid, Dad and my brother build up some nice aluminum 24" clincher rims on it. One thing I remember about it was tires were always VERY TIGHT when mounting them. It is like one had to use a heavy duty screwdriver to get the tire on or off. We never did figure out why.

I now wonder if maybe rim sizes were off just enough. A 27" (630), and 700c (622) are incompatible, 8mm difference. So, I find it unlikely we were able to mount a 540 tire onto a 547 rim. But, perhaps even mounting a 540 tire onto a 541 rim could be tight, especially if we had thick rim tape.

Anyway, perhaps over the next few decades, people will adhere to more standards, and the oddball bikes will get relegated to vintage curiosities. Nonetheless, quite a few old bikes are still on the road, and will remain on the road for quite some time. Will we ever just give up the inch notations?

Once upon a time in the Pleistocene...

Before the 1970's, there was basically no market for adult bikes. 26" = ETRTO 559 was the cruiser bike size for teenagers and beach resorts. These cruiser bikes were used as the basis for the earliest mountain bikes, which had a boom in the 80's, and proliferated.

I think the old Raleigh and Robin Hood 3 speeds were around at least back into the 50's, often sporting 26" wheels.

And, a few made their way here to the USA.

But, alas, the old Raleigh 26" bikes and old Beach Cruiser 26" bikes had different rim sizes.

I remember my grandparents had some ancient balloon tire bikes in their barn when I was a kid. But, other than the Schwinn Stingray bikes, I don't remember anybody using the fat tire bikes until the 80's when they must have chosen to start crossing the old cruisers with road bikes or stingray bikes to make some new monstrosity.

Perhaps one of the more recent changes is the availability of wide and narrow tire sizes for any specific rim diameter. So, 26x1.5, BSD 559 may be a relatively new tire size for those wanting sportier tires for the MTB rims.

As I understand it, 650b (584 BSD) was a relatively narrow 26" tire, but MTB riders have now adopted it as a mid sized 28" wheel/rim size. I suppose re-purposing an old rim size with new wider tires makes some sense, rather than introducing a new rim size.

Here's a forum post from Kirk Pacenti that talks about why 650b and not 650a:

Why not 650A instead of 650B?- Mtbr.com

He was taking a risk by funding a run of mountain-bike tires in an unproven size. He was after something in between the 26er and 29er sizes of the day. He needed for rims to be readily available. And it was important to him that conversions be possible on existing, 26er frames of the day. So 650b it was.

Decades ago I had so much trouble trying to buy a 26 X 1 1/2 tire that fit that I quit riding the bike. Stores kept selling me 26 X 1 3/8 saying they were the same. (This was years before internet, research was difficult back then.) My 26 inch bike was 650b. Now the marketing pros are trying to resurrect 650b by calling it a new size, 27.5.

Skinny 26ers have been around for ages. This was one of my faves BITD:

Avocet Bike Tires - the Buyer's Guide, 2015

And yep, 650 B is generally used for 584 tires less than 48mm or so, with 27.5" generally reserved for wider tires. Similar to 700c vs 29".

The confusion extends to 28 inch wheels as well.700 x 38c tires often have markings that read 28 X 1 5/8.
A couple of weeks ago, guy wheels a dutch bike into the shop with a couple of brand new tires hung from the handlebar, asking if we can install them for him. Without even looking at the sidewall of his existing tires, I told him his new Continentals were not going to fit.
622 tires will never fit on 635 rims.

Yes, that is why for clarity it is better to use ETRTO numbers.

French scheme had an a, b, c .. nominal tire, wheel similar overall diameter..

progressed from smaller rim, fatter tire, to larger rim, and thinner tire.

Another size that has always been tough to find is the old Schwinn Hurricane Tandem tire, 26x 1.5", a "euro" size used on Town and Country Tandems and the rare Welterweight in the day.
Just when you thought you had it figured out.

David

Is that the Schwinn S4? AKA 584mm?

Not too tough to find. https://www.biketiresdirect.com/prod...iABEgJYB_D_BwE

Yes it is. Roger

In 1991, Schwinn Miradas (and the model below, the Frontier) used 26 x 1-1/2 tires which are actually 650 B size.