Confusing tire issue
 

Ok...just for fun I decided to see if the set of newer 26" X 1 3/8" tires I have lying around would fit on a bike that now has old worn 26" X 1.75" tires on it. When I went to put the 26 x 1 3/8" tire on the rim it was way too big in diameter yet it's supposed to be 26" in diameter just like the old tire....I am confused.

you can't mix fractional sizes and decimal sizes.

the BSD on those two are totally different. 26 1-3/8, aka: 27.5'er

check sheldon brown website about tire sizes

Ahhhh...Ok...I had no idea! Thanks so much for clearing that up for me! I am going to check Sheldon Brown's site now. :D

Let me help: http://www.sheldonbrown.com/tire_sizing.html
I have this bookmarked- I seem to point at it every other day.

Cool, thanks I now have his site bookmarked too. ;) I am a newbie when it comes to this stuff.

I just bought a couple of old bikes and I am trying to refurbish them a bit since over all they are in good shape except for a couple of things like tires and one bike needs better gear shifters and shift cables.

I have one more tire/rim question since I am here. I noticed on the bike with the 26 X 1.75 tire the rims say 26" x 1.50 on them. Does it matter that it now has 26 x 1.75" tires on it? Since I am going to buy tires anyway should I get 26 x 1.50 inch tires.? My local Mountain Equipment Co-Op advertises a nice slick (yet heavy @ 500gr) 26 x 1.50 tire for less than $10. Seeing as I only ride 2 miles to work and then just use it to run short errands I don't think I need anything better than this? I mean I only paid $40 for the bike.

Thanks again for the help!

All rims can receive a ride range of tire widths. While some rims include a tire width suggestion, it is only that - there is absolutely no problem using a 26x1.50 rim with a 26x1.75 or 26x2.00 tire.

A narrower tire requires a higher inflation pressure and rides more harshly (less comfortable). It has a lower rolling resistance (it is faster).

A wider tire requires a lower inflation pressure and is more comfortable, yet slower.

Either a 26x1.50 or a 26x1.75 tire would be fine for you - a slick is ideal if you don't go offroad.

Thanks again for the helpful tips. I never go off road except maybe to cut through a city park...on grass. I think slicks would do me just fine. ;) I like the idea of "less rolling resistance" so I think I will try the 26 x 1.50 size.

What are the ISO size markings on the tires? If they don't match, that could be your problem.

I have not checked the ISO markings but...according to the second person to post and also Sheldon Browns website....You cannot use a tire that has a fractional size markings on a rim designed for tires marked in decimal sizes. For example, a rim that says it takes takes 1.75" tires will not fit a tire marked 1 1/4". It has to be a tire with a .75" decimal not a 1/4" fraction.

Just to add to the confusion, some manufacturers, such as Continental, list 20 x 1 1/8 for a 406/20" wheel or 26 x 1 1/8 for 559/26", among other fractional offerings.
Primo lists a 20 x 1 3/8 for 451/20". These are modern tires for modern wheels. Most tires for 406 and 559 are decimal. Not sure about 451.

So ETRTO came in and said let's make sense of this mess. The fact was (and is) that these tire size ratings have little to do with reality. Well, we never went ahead and got rid of the odd names such as 26x1-3/8 but at least every tire is marked with ETRTO sizes as well. So for example, 27x1-1/4 is 630x32mm, and that's actual size.

Schwinn and others made up some wacky sizes that sound nominally (or numerically) the same as other sizes, e.g. 26x1.375 which is numerically the same as 26x1-3/8. Well guess what. The 26 is where it varies. Actual diameter is different. It's enough to drive a bike mechanic insane.

26 x 1 3/8 BSD = 590
26 x 1.75 BSD = 559

No, there are tyres and rims out there without a marked size.

Anyone who uses 20"/451 wheels and tires is insane. I have a half-dozen 451 tires and 4 or 5 rims, so I'll just have to change my sig to read "insane quantum bicycle mechanic" (per Tom Reingold).

So there. :twitchy:

Why, thank you, Jeff!