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Tire size question

Old 09-01-17, 11:34 AM
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Tire size question

I have a 1995 Trek 820 mountain bike. It has 26x195 tires. I was thinking of putting a smaller road tire on the bike. What i would be the smallest tire that would be appropriate for the factory wheels. 26x1.75 , 26x1 3/8 ?

Thanks, Jim
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Old 09-01-17, 11:58 AM
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Originally Posted by Trazam1986
I have a 1995 Trek 820 mountain bike. It has 26x195 tires. I was thinking of putting a smaller road tire on the bike. What i would be the smallest tire that would be appropriate for the factory wheels. 26x1.75 , 26x1 3/8 ?

Thanks, Jim
Don't get the 1-3/8.

1.75 will be fine. 1.5 or 1.4 might also work.
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Old 09-01-17, 12:03 PM
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You could probably go down to 35mm but it would look a little funny.
To be sure, you should measure the inside of your rims... some wide MTB rims will have trouble with narrow tires.

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Old 09-01-17, 12:37 PM
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Originally Posted by Trazam1986
I have a 1995 Trek 820 mountain bike. It has 26x195 tires. I was thinking of putting a smaller road tire on the bike. What i would be the smallest tire that would be appropriate for the factory wheels. 26x1.75 , 26x1 3/8 ?

Thanks, Jim
Do NOT get a tire labelled "26 x 1 3/8." Fractional width sizing typically refers to wheels of a different bead seat diameter than what you have, and such a tire would likely not fit on your rim at all. 26er tires where the widths are specified in decimal numbers generally refer to a BSD of 559, which is what you have. So if you want a tire that's 1 3/8 inches wide, you'll want something like 26x1.375 (although, I've never heard of a 26er tire in that exact width).

As for what would be appropriate... according to the catalogs, your original rims have an inner width of 19mm, which means that they'll be reasonably happy with just about anything that isn't a fatbike tire.

But also. If your goal is road performance, you shouldn't worry very much about minimizing width. Within reason, width is a relatively insignificant factor in paved performance. Narrow tires work fine on the road, but don't get a narrow tire just because it's narrow. I've ridden fast 2" road tires, and I've ridden slow 1" road tires, and I've ridden slow 2" road tires, and I've ridden fast 1" road tires. In my experience, if you want to go fast, get a fast tire.
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Old 09-01-17, 12:59 PM
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I have a MTB with similar rims, and I have used a 26x1.4 Michelin on it before (labelled a 35-559 as I recall). I generally felt it was too narrow and they're just hanging in my shop right now.

I found a 26x1.75 (about 44-559) to be a great size. I run semi-slicks on my MTBs with this size rim.
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Old 09-01-17, 01:26 PM
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Thank you! I appreciate you sharing your experience. Y ou may have saved me from having a set of 1.4's hanging in the garage as well.
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Old 09-01-17, 01:32 PM
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in 559 26" a narrow compatible tire would be 1.5" thereabouts..

a 26 by 1 3/8 may not be 559 26", but made for a 3 speed with a bigger rim diameter.. incompatible.




...
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Old 09-01-17, 01:38 PM
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[QUOTE= Narrow tires work fine on the road, but don't get a narrow tire just because it's narrow. I've ridden fast 2" road tires, and I've ridden slow 1" road tires, and I've ridden slow 2" road tires, and I've ridden fast 1" road tires. In my experience, if you want to go fast, get a fast tire.[/QUOTE]



Thanks. Not worried about going too fast, just looking for a little smoother ride on pavement while riding with the kids. most of the smoother road tires seem to be 1.75
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Old 09-01-17, 01:49 PM
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Yep -- 1.75" will be great. I use Michelin Country Rock tires on mine in that size (the only size they make in this tire). It has a smooth tread and is very supple. And actually fairly light for their price (only 560 grams, and they're 20-25 bucks each). I usually run mine at 20-40 psi front-rear and they're SMOOTH.
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Old 09-01-17, 02:11 PM
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Originally Posted by hokiefyd
Yep -- 1.75" will be great. I use Michelin Country Rock tires on mine in that size (the only size they make in this tire). It has a smooth tread and is very supple. And actually fairly light for their price (only 560 grams, and they're 20-25 bucks each). I usually run mine at 20-40 psi front-rear and they're SMOOTH.
Some tires are listed as "Raised Center" why would I want, or not want these?
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Old 09-01-17, 02:19 PM
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Originally Posted by Trazam1986
Some tires are listed as "Raised Center" why would I want, or not want these?
The idea is that you'd have a smooth part for going fast on paved roads and tread/knobs for turning in the dirt. The reality is the idea doesn't work that well.

For street only use (maybe some occasional gravel sections), I'd get slicks or minimal tread and no raised center.

Pick one out and post it so we can give you our opinions.
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Old 09-01-17, 02:44 PM
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My grail 26er road tire is the extralight carcass Compass Naches Pass. It's tough for me to spend $84 on a tire, though.

We have 1.5 Pasela on the tandem now. Nice ride, but they collect quite a few micro pebbles, even more than the Michelin Country Rocks I have on my cruiser.

I've run 1.4 on the little lady's '95 820 and thought they worked well - the stock rims are about 25 outer width, probably 19-ish inner.
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Old 09-01-17, 02:45 PM
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My 26"X1.25" look just fine on "standard" mountain bike rims.
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Old 09-01-17, 03:50 PM
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Originally Posted by Trazam1986
Some tires are listed as "Raised Center" why would I want, or not want these?
Some road tires advertise a raised centerline for low rolling resistance. It's based on the theory that big contact patches are what causes low-PSI rolling resistance. The thing is, that theory is just completely wrong; energy lost deforming the tire is what causes low-PSI rolling resistance.

That's not to say that thicker tread rubber at the centerline is a bad idea. It can increase wear life and slightly aid against punctures, with minimal compromise to ride quality and weight. But, if that's the goal, it's arguably better to have the tread thickness gradually increase toward the center than have the centerline abruptly "raised", since an abruptly raised area can degrade the feel of cornering.

Originally Posted by Trazam1986
just looking for a little smoother ride on pavement
The smoothest-riding 26er road tire that I'm aware of is probably the 2.1" Compass Rat Trap Pass Extralight. If I wasn't willing to spend $84 on a tire, I'd probably think about 1.75" Panaracer Paselas instead.

Last edited by HTupolev; 09-01-17 at 03:53 PM.
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Old 09-01-17, 04:34 PM
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Originally Posted by Bill Kapaun
My 26"X1.25" look just fine on "standard" mountain bike rims.
We put 26x1.25" slicks on my son's vintage rigid fork mtn bike. I would never have gone that small, but he wanted it. Turned out to be a total kick to ride. It's so responsive on the road it's almost twitchy. It completely transformed the bike. The only disadvantage is you're forced to buy smaller tubes as the normal 1.5" tubes just won't fit. The tires we bought were Forte, with a Kevlar belt, but I couldn't find the same model on their website just now.

Another one I've considered is a Ritchey, iirc, in 1.4". I put Kendra 1.5" slicks on my rigid fork mtn bike to make it a commuter, but those tires (or size) did not have such a positive effective on the handling, although there are size, geometry and setup differences between the two frames.
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Old 09-01-17, 05:37 PM
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Originally Posted by Trazam1986
I have a 1995 Trek 820 mountain bike. It has 26x195 tires. I was thinking of putting a smaller road tire on the bike. What i would be the smallest tire that would be appropriate for the factory wheels. 26x1.75 , 26x1 3/8 ?
You need to use the ETRTO tire size designations to find an appropriate tire. There are at least six mutually incompatible rim sizes that claim a nominal 26" diameter. Any tire manufactured within the past couple decades should have an ETRTO size designation molded into the sidewall in addition to the nominal designations. Your nominal 26" x 1.95" tires likely have an ETRTO size of 50-559, so look for a pair of numbers like that, separated by a hyphen.

The first (smaller) number of the pair is the tire width in millimeters. Rims can accept a variety of widths, so if you want a somewhat narrower tire, look for one where the first number in the ETRTO size is somewhat smaller than your current tire, e.g. 45-559 or 38-559.

The second (larger) number in the ETRTO size is the tire bead seat diameter in millimeters, and this must match your rim or the tire won't mount. A nominal 26"x 1-3/8" tire may have an ETRTO size of 35-590, which would not work on a 559mm rim (assuming that's what you have).
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Old 09-01-17, 06:26 PM
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You can also mix. I put a 26 x1.5 slick on the front of my Trek 930 rigid mtb, and a 26x1.75 on back. Since I weigh 265 lbs, i wanted a bit more rubber on the rear.
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Old 09-02-17, 03:53 PM
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Originally Posted by Bill Kapaun
My 26"X1.25" look just fine on "standard" mountain bike rims.
+1. Way back when, I put 26 x 1.25" Tioga City Slickers on my MTB when my "everyday" bike's frame broke. I was surprised that they were quite fast on normal pavement and comfortable at 100psi.
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Old 09-03-17, 12:27 PM
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I've gotten many happy miles out of the 26"x1.75" (42-559 I think) Panaracer Pasela. Cheap for how well they roll. I have no interest in converting to narrower tires on that bike, and lust after the 1.8" Compass Naches Pass when they do wear out. 😉
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Old 09-03-17, 04:34 PM
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Originally Posted by JohnDThompson
You need to use the ETRTO tire size designations to find an appropriate tire. There are at least six mutually incompatible rim sizes that claim a nominal 26" diameter. Any tire manufactured within the past couple decades should have an ETRTO size designation molded into the sidewall in addition to the nominal designations. Your nominal 26" x 1.95" tires likely have an ETRTO size of 50-559, so look for a pair of numbers like that, separated by a hyphen.

The first (smaller) number of the pair is the tire width in millimeters. Rims can accept a variety of widths, so if you want a somewhat narrower tire, look for one where the first number in the ETRTO size is somewhat smaller than your current tire, e.g. 45-559 or 38-559.

The second (larger) number in the ETRTO size is the tire bead seat diameter in millimeters, and this must match your rim or the tire won't mount. A nominal 26"x 1-3/8" tire may have an ETRTO size of 35-590, which would not work on a 559mm rim (assuming that's what you have).
I'm pretty surprised by this. I'm not much of a mountain bike guy, but the three times I've bought Mtn bike tires (for three different vintage rigid fork bikes) I just walked into the store and bought 26" tires.

So, now that I'm clued into the tire markings, are there equivalent numbers on vintage (or modern) rims?
I've got some vintage road rims with no markings. With these I have to try a tire to determine if 700cc or 27".
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Old 09-03-17, 05:01 PM
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Originally Posted by sunburst
I'm pretty surprised by this. I'm not much of a mountain bike guy, but the three times I've bought Mtn bike tires (for three different vintage rigid fork bikes) I just walked into the store and bought 26" tires.
The vast majority of "26 inch" wheels/tires out there today are "26ers", with a bead seat diameter of 559mm. When specifying their sizes with inches, the width is generally specified as a decimal number, i.e. 26 x 1.5.

However: https://www.sheldonbrown.com/26.html
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Old 09-03-17, 06:12 PM
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Originally Posted by sunburst
I'm pretty surprised by this. I'm not much of a mountain bike guy, but the three times I've bought Mtn bike tires (for three different vintage rigid fork bikes) I just walked into the store and bought 26" tires.
26" tires and rims in particular are a hot mess:

https://www.sheldonbrown.com/26.html

So, now that I'm clued into the tire markings, are there equivalent numbers on vintage (or modern) rims? I've got some vintage road rims with no markings. With these I have to try a tire to determine if 700cc or 27".
You're right, vintage rims and tires in particular are sometimes unmarked. If neither the rim nor tire on your wheel has a size marked, you need to measure the bead seat diameter (the diameter across the rim from place where the tire bead seats inside the rim). a 700C rim or tire will measure 622mm (hence the ETRTO size "622") while a 27" rim or tire will measure 630mm (ETRTO 630).
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Old 09-03-17, 09:31 PM
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Originally Posted by JohnDThompson

You're right, vintage rims and tires in particular are sometimes unmarked. If neither the rim nor tire on your wheel has a size marked, you need to measure the bead seat diameter (the diameter across the rim from place where the tire bead seats inside the rim). a 700C rim or tire will measure 622mm (hence the ETRTO size "622") while a 27" rim or tire will measure 630mm (ETRTO 630).
Or you can do it the old-fashioned way: try it. If the tire won't go on, or goes on with great difficulty and won't seat, you probably have a 700C tire and 27" rim. If the tire goes on super-easily and the tube explodes in your ear as soon as you pump it up, you probably have a 700C rim and 27" tire.

Back in my bike shop days in the early '80's, we stocked several tires in 700C and 27" versions. Life was really interesting then.
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