28mm tires only 24mm wide!?

[Ron Ruff]

I've been using 28mm Continental Ultra 3000s, and they always seemed
rather small for 28s. Today I thought I'd measure the actual width and
depth... and was surprised to find that they aren't even close! The
width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
measured from the edge of the rim.

Just wondering what other's experience has been with tires. Do all
manufacturers tend to overstate the width of their tires this much?

-Ron

 

[David L. Johnson]

On Sat, 20 Aug 2005 04:23:09 -0700, Ron Ruff wrote:

> I've been using 28mm Continental Ultra 3000s, and they always seemed
> rather small for 28s. Today I thought I'd measure the actual width and
> depth... and was surprised to find that they aren't even close! The
> width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
> measured from the edge of the rim.
>
> Just wondering what other's experience has been with tires. Do all
> manufacturers tend to overstate the width of their tires this much?
>
It is a common phenomenon. Think about two companies. Company A sells a
28mm tire that actually measures 28mm across, and so it weighs 280g, with
a max inflation pressure of 90psi. Company C markets their "28" as
weighing 240g and having a max inflation pressure of 100psi. What they
don't mention is that it's actually 23mm across. Which would people be
more likely to buy?

On the other hand, the width of the tire depends on the rim width as well.
Wider rim, wider tire.

--

David L. Johnson

__o | When you are up to your ass in alligators, it's hard to remember
_`\(,_ | that your initial objective was to drain the swamp. -- LBJ
(_)/ (_) |

 

[Kinky Cowboy]

On 20 Aug 2005 04:23:09 -0700, "Ron Ruff" <[email protected]>
wrote:

>I've been using 28mm Continental Ultra 3000s, and they always seemed
>rather small for 28s. Today I thought I'd measure the actual width and
>depth... and was surprised to find that they aren't even close! The
>width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
>measured from the edge of the rim.
>
>Just wondering what other's experience has been with tires. Do all
>manufacturers tend to overstate the width of their tires this much?
>
>-Ron

My Conti measurements
GP Supersonic 20c 21.0mm wide
UltraSport 23c 22.5mm wide
SportContact 37c 34.7mm wide

All on rims 19.5-20mm overall width.

Your depth measurement probably equates to something close to 28mm
from the bead seat (i.e. the bit that's 622mm in diameter) and this is
usually the critical measure for clearance. If your frame is supposed
to take 28c tyres, that's a diameter of 622+(2x28)=678mm, and tyre
manufacturers will want to keep a "28c" tyre at or below this overall
diameter for all practical rim widths to allow you to buy tyres with
some confidence that they won't rub on your fork crown.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

 

[John Forrest Tomlinson]

On 20 Aug 2005 04:23:09 -0700, "Ron Ruff" <[email protected]>
wrote:

>Just wondering what other's
>experience has been with tires. Do all
>manufacturers tend to overstate the
>width of their tires this much?

It's common.

JT

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[philcycles]

Ron Ruff wrote:
> I've been using 28mm Continental Ultra 3000s, and they always seemed
> rather small for 28s. Today I thought I'd measure the actual width and
> depth... and was surprised to find that they aren't even close! The
> width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
> measured from the edge of the rim.
>
> Just wondering what other's experience has been with tires. Do all
> manufacturers tend to overstate the width of their tires this much?
>
> -Ron

As with almost any situation either "Casablanca" or "The Godfather"
provide tha relevant quote. To paraphrase Capt. Renault, "I am shocked
to discover marketing going on here."
Phil Brown

 

[Paul Cassel]

David L. Johnson wrote:

> It is a common phenomenon. Think about two companies. Company A sells a
> 28mm tire that actually measures 28mm across, and so it weighs 280g, with
> a max inflation pressure of 90psi. Company C markets their "28" as
> weighing 240g and having a max inflation pressure of 100psi. What they
> don't mention is that it's actually 23mm across. Which would people be
> more likely to buy?
>
> On the other hand, the width of the tire depends on the rim width as well.
> Wider rim, wider tire.
>
Pretty cynical response, but that doesn't mean you are even slightly
wrong. Over in women's dresses there has been this phenom called size
creep. Folks began selling women's dresses mislabled so they'd make a 10
and label it an 8. Obviously the women would buy 8's over 10's if they
could.

Today a size 8 is the same as a size 12 when I was a kid. Yes, it worked
so all did it.

 

[m-gineering]

Ron Ruff wrote:
>
> I've been using 28mm Continental Ultra 3000s, and they always seemed
> rather small for 28s. Today I thought I'd measure the actual width and
> depth... and was surprised to find that they aren't even close! The
> width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
> measured from the edge of the rim.
>
> Just wondering what other's experience has been with tires. Do all
> manufacturers tend to overstate the width of their tires this much?
>
> -Ron

this is compensated by making the opposite mistake in the weight column

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

 

[John Everett]

On 20 Aug 2005 04:23:09 -0700, "Ron Ruff" <[email protected]>
wrote:

>I've been using 28mm Continental Ultra 3000s, and they always seemed
>rather small for 28s. Today I thought I'd measure the actual width and
>depth... and was surprised to find that they aren't even close! The
>width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
>measured from the edge of the rim.
>
>Just wondering what other's experience has been with tires. Do all
>manufacturers tend to overstate the width of their tires this much?

It's not a real surprise. I've ridden for years with Michelin 700 x
20s on my "racing bikes". Last year I found some Hutchinson Carbon
Comp 700 x 23s on sale, so I bought a pair. After replacing an old set
of Michelins I thought I'd need to reset the circumference in my
computers. Turns out the Hutchinson's are EXACTLY the same
circumference as the Michelins they replaced.


jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

 

[[email protected]]

John Everett wrote:

> It's not a real surprise. I've ridden for years with Michelin 700 x
> 20s on my "racing bikes". Last year I found some Hutchinson Carbon
> Comp 700 x 23s on sale, so I bought a pair. After replacing an old set
> of Michelins I thought I'd need to reset the circumference in my
> computers. Turns out the Hutchinson's are EXACTLY the same
> circumference as the Michelins they replaced.

Evidently, a narrow tire has a more elliptical profile when inflated
than a fatter tire on the same width rim. The fatter tire has a wider
contact patch, but the actual circumference doesn't vary much at the
same psi and under load. My 700x24c tubulars are considerably fatter
than their 700x21c counterparts, but the difference in measured rollout
between the two sizes is only 13mm, which is less than 1%.

 

[IMKen]

And you thought it was all those trips up to Maloa'a that made you faster.


Ken


"Ron Ruff" <[email protected]> wrote in message
news:[email protected]...
> I've been using 28mm Continental Ultra 3000s, and they always seemed
> rather small for 28s. Today I thought I'd measure the actual width and
> depth... and was surprised to find that they aren't even close! The
> width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
> measured from the edge of the rim.
>
> Just wondering what other's experience has been with tires. Do all
> manufacturers tend to overstate the width of their tires this much?
>
> -Ron
>

 

[Ron Ruff]

[email protected] wrote:
> My 700x24c tubulars are considerably fatter
> than their 700x21c counterparts, but the difference in measured rollout
> between the two sizes is only 13mm, which is less than 1%.

13mm/pi/2 = 2.1mm actual height difference... which is fairly close to
the stated 3mm size difference.

Just wishing there was a way to tell what the true size of a tire would
be without actually trying it. For training I like the size I have, but
for racing I'd prefer something 21.5-22mm wide, as I hear that is as
wide as I could go without screwing up the aerodynamics of the rims. Of
course, if they made the rims a little wider, then tires could be a
little wider without causing flow separation.

As I recall the old Supercomps from around 1990 had a huge jump from
the 20c to 23c size... the 20c was about right, but the 23c was
actually 26mm wide! Still, Fignon rode those fat tires (looked like old
white-walls) in some stages in the Tour... and did quite well. He
mentioned that he prefered their comfort.

 

[Michael Press]

In article <[email protected]>,
Paul Cassel <[email protected]> wrote:

> David L. Johnson wrote:
>
> > It is a common phenomenon. Think about two companies. Company A sells a
> > 28mm tire that actually measures 28mm across, and so it weighs 280g, with
> > a max inflation pressure of 90psi. Company C markets their "28" as
> > weighing 240g and having a max inflation pressure of 100psi. What they
> > don't mention is that it's actually 23mm across. Which would people be
> > more likely to buy?
> >
> > On the other hand, the width of the tire depends on the rim width as well.
> > Wider rim, wider tire.
> >
> Pretty cynical response, but that doesn't mean you are even slightly
> wrong. Over in women's dresses there has been this phenom called size
> creep. Folks began selling women's dresses mislabled so they'd make a 10
> and label it an 8. Obviously the women would buy 8's over 10's if they
> could.
>
> Today a size 8 is the same as a size 12 when I was a kid. Yes, it worked
> so all did it.

A well known apparel maker sells trousers for women that
are labeled 'Slim Fit.' Wife has them. I said "They have a
good thing going."

--
Michael Press

 

[Nick Payne]

Yeah, the sizing label on a cycling jersey I purchased in Switzerland last
year said it was an XL size in Japan, an L in Europe, and only an M in the
US....guess who the clothing manufacturers know are lardarses...

Nick

 

[Ron Ruff]

Kinky Cowboy wrote:
> If your frame is supposed
> to take 28c tyres, that's a diameter of 622+(2x28)=678mm, and tyre
> manufacturers will want to keep a "28c" tyre at or below this overall
> diameter for all practical rim widths to allow you to buy tyres with
> some confidence that they won't rub on your fork crown.
>

At first I thought you must be right, then I recalled that I needed to
set the wheel diameter smaller than what was recommended for my cycle
computer (Sigma). So I looked up their chart, and they list a setting
of 2149mm for a 700x28c wheel. ((2149/pi)-622)/2 = 31.0mm for the tire
depth relative to the bead... and for this to be correct it would have
to be at the squashed part of the tire under load!

So Sigma at least thinks that a typical 28c tire is quite a bit deeper
than 28mm at the bead... more like 34-35mm.

 

[Mark Hickey]

Michael Press <[email protected]> wrote:

>A well known apparel maker sells trousers for women that
>are labeled 'Slim Fit.' Wife has them. I said "They have a
>good thing going."

Then you ducked? ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

 

[Ningi]

David L. Johnson wrote:
> On Sat, 20 Aug 2005 04:23:09 -0700, Ron Ruff wrote:
>
>
>>I've been using 28mm Continental Ultra 3000s, and they always seemed
>>rather small for 28s. Today I thought I'd measure the actual width and
>>depth... and was surprised to find that they aren't even close! The
>>width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
>>measured from the edge of the rim.
>>
>>Just wondering what other's experience has been with tires. Do all
>>manufacturers tend to overstate the width of their tires this much?
>>
>
> It is a common phenomenon. Think about two companies. Company A sells a
> 28mm tire that actually measures 28mm across, and so it weighs 280g, with
> a max inflation pressure of 90psi. Company C markets their "28" as
> weighing 240g and having a max inflation pressure of 100psi. What they
> don't mention is that it's actually 23mm across. Which would people be
> more likely to buy?
>

I found this out today. I have Panaracer T-Serv 25mm tyres on my bike.
My cycling buddy has Bontrager Race X Lite 23mm tyres. We compared
them today and my 25's are noticeably narrower than his 23's. So,
theory above can be supported by at least some evidence

Pete

 

[Alex Rodriguez]

In article <[email protected]>,
[email protected] says...
>
>
>I've been using 28mm Continental Ultra 3000s, and they always seemed
>rather small for 28s. Today I thought I'd measure the actual width and
>depth... and was surprised to find that they aren't even close! The
>width is only about 15/16in (23.8mm) and the depth 7/8in (22.2mm)
>measured from the edge of the rim.
>
>Just wondering what other's experience has been with tires. Do all
>manufacturers tend to overstate the width of their tires this much?

Rim width will also affect tire width. How wide are your rims?
--------------
Alex

 

[Ron Ruff]

Alex Rodriguez wrote:
>
> Rim width will also affect tire width. How wide are your rims?

They are Mavic CXP22s. They say 622x15 on the side.

 

[Rob Shields]

On Sun, 21 Aug 2005 15:31:15 +0000, Ningi wrote:

> I found this out today. I have Panaracer T-Serv 25mm tyres on
> my bike.
> My cycling buddy has Bontrager Race X Lite 23mm tyres. We compared
> them today and my 25's are noticeably narrower than his 23's. So,
> theory above can be supported by at least some evidence
>
> Pete

My Panaracer Pasela 28s are 25mm wide. My Conti Gatorskin 32s are 27mm.
My Armadillo 25s and vitoria rubino 23s seem more realistic.

Rob

 

[Mark Hickey]

Rob Shields <[email protected]> wrote:

>On Sun, 21 Aug 2005 15:31:15 +0000, Ningi wrote:
>
>> I found this out today. I have Panaracer T-Serv 25mm tyres on
>> my bike.
>> My cycling buddy has Bontrager Race X Lite 23mm tyres. We compared
>> them today and my 25's are noticeably narrower than his 23's. So,
>> theory above can be supported by at least some evidence
>>
>> Pete
>
>My Panaracer Pasela 28s are 25mm wide. My Conti Gatorskin 32s are 27mm.
>My Armadillo 25s and vitoria rubino 23s seem more realistic.

My Panaracer T-Serv 25's are a but under 24mm, but the T-Serv 35mm
meaures close to 37mm. Still, pretty close on the "tire size
relativity scale".

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame