Tires for 559-18 and 559-20 Rims

I have two bicycles in the fleet that I want to replace the tires on.
One has 559-18 rims, and presently has 26 x 1.95" tires. One has 559-20
rims, and presently has 26 x 1.95" tires.

If I extrapolate from the chart on Sheldon's web site, it appears as if
the 559-20 rim can take 32mm-47mm tires (1.25"-1.85") and the 559-18 rim
can take 27mm-40mm tires (1.1-1.6" tires).

Is it okay to put 26 x 1.25" tires on the 20mm wide rim?

SMS wrote:

I have two bicycles in the fleet that I want to replace the tires on.
One has 559-18 rims, and presently has 26 x 1.95" tires. One has 559-20
rims, and presently has 26 x 1.95" tires.

If I extrapolate from the chart on Sheldon's web site, it appears as if
the 559-20 rim can take 32mm-47mm tires (1.25"-1.85") and the 559-18 rim
can take 27mm-40mm tires (1.1-1.6" tires).

Is it okay to put 26 x 1.25" tires on the 20mm wide rim?

Why wouldn't it be? I won't use a tire that is the same width as the
rim or narrower when inflated, but up to that point anything goes. Be
advised that ride quality suffers when the rim approaches the same
width as the tire. You may have to run lower pressure to
compensate.

What do you intend to do with 1.25" tires that you couldn't do with
1.5" tires that would probably ride better?

Chalo

Chalo wrote:

snip

Why wouldn't it be? I won't use a tire that is the same width as the
rim or narrower when inflated, but up to that point anything goes. Be
advised that ride quality suffers when the rim approaches the same
width as the tire. You may have to run lower pressure to
compensate.

What do you intend to do with 1.25" tires that you couldn't do with
1.5" tires that would probably ride better?

Chalo


The 26 x 1.5" tires aren't available in as high a pressure rating as the
1.25". Other than that, I don't really care about 1.5" versus 1.25". 26"
x 1.25" are available in 125 psi max, while the 26" x 1.5" are rated at
60 psi max. I wouldn't go to 125 psi, but I'd like to go to 80 psi.

What I was worried about is what you pointed out, about having to run
lower pressure with the narrower tire, but it appears as if 1.25" is
still wide enough for a 20mm rim that this won't be an issue.

On Mon, 17 Nov 2008 22:03:28 -0800, SMS
may have said:

I have two bicycles in the fleet that I want to replace the tires on.
One has 559-18 rims, and presently has 26 x 1.95" tires. One has 559-20
rims, and presently has 26 x 1.95" tires.

If I extrapolate from the chart on Sheldon's web site, it appears as if
the 559-20 rim can take 32mm-47mm tires (1.25"-1.85") and the 559-18 rim
can take 27mm-40mm tires (1.1-1.6" tires).

Is it okay to put 26 x 1.25" tires on the 20mm wide rim?

Yes.

Manufacturers regularly violate the guidelines in that chart with
their mountain bike setups by putting wider tires on narrow rims.
Going the other way is less often seen, but the size setup you cite is
certainly acceptable; in fact, by your own numbers it is within the
range for the rim. It would only become questionable beyond that
range.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

In article ,
SMS wrote:

I have two bicycles in the fleet that I want to replace the tires on.
One has 559-18 rims, and presently has 26 x 1.95" tires. One has
559-20 rims, and presently has 26 x 1.95" tires.

If I extrapolate from the chart on Sheldon's web site, it appears as
if the 559-20 rim can take 32mm-47mm tires (1.25"-1.85") and the
559-18 rim can take 27mm-40mm tires (1.1-1.6" tires).

Is it okay to put 26 x 1.25" tires on the 20mm wide rim?

Yes. I have run this combination on one bike for about 12 years without
any problems. A 1.25 is about 32 mm wide; I've even used 26 x 1.0
without any problems.