why aren't tires the size they say they are.

[bicycletricycle]

Why aren't tires the size they say they are? Is it that hard to put a tire on a rim, measure it, and then write that size on the tire, or even just write in the detailed description the tires idiosyncrasies. Obviously tire size will depend on rim width some but that's fine, just list the description the tires real width on a rim of the manufacturers choosing. Anything would help.

Currently I have this silly situation

700x28 conti GP4000 IIs on TB14s that measure 30.5 millimeters
700x32 compass stampede pass on PL23 that measure 29 millimeters

I was hoping to try a slightly larger tire so I ordered a larger tire and I got a smaller tire. (obviously different manufacturer)(I really like the conti's and I am sure I will like the compass tires but its still mildly frustrating)

both of these rims are 23 millimeters wide, obviously there are differences between them but *** tire manufacturers. Measure your tires please.

Am I missing something?

Rant over.

[benb]

http://velonews.competitor.com/2016/05/bikes-and-tech/technical-faq-why-are-labeled-tire-sizes-inconsistent_406275

Some timely info there, that came out yesterday.

[bicycletricycle]

That article is interesting but just amounts to a bunch of technical rubbish used as an excuse IMHO. Depends on the rim, depends on inflation pressures, depends on the rim strip, depends on tolerances, etc.

Sure, everything depends on everything, they still might want to make an effort to more adequately describe tire widths in ways that help actual users decide on what they want. Leaning back and saying, "well we have an internal technical specification that we are satisfied with" is no help.

the original question was great, why is a continental gatorskin tire 4 millimeters smaller than a 4000IIs, same manufacturer, same rim, same user, same everything. I have also been curious about this inconsistency.


No direct answer from continental guy.

Not sure if the other tire manufacturers are more internally consistent, I have not purchased all the tires from all the companies....... yet :)

[happycampyer]

Regarding your Compass tires, my experience is that when first mounted they measure on the small side, but over time expand by several millimeters. What's interesting to me is that they don't seem to expand just from being inflated sitting on the rim unridden--it seems to take a fair amount of riding for them to expand. I noticed that FMB tubulars expand quite a bit, too, but never had a pair inflated pre-use for an extended time to see if it took the extra pressure of riding to get them to expand. It makes common sense I suppose, but as that other thread shows it would take a study to prove that it is the case.

[SeanScott]

Yeah, I was pretty bummed when my Vittoria Corsa CXs 25s inflated to past a 28 and wouldn't work on my bike.

[wombatspeed]

I hear ya!

And on top of that there is internal inconsistency WITHIN the same manufacturer and tire model.

My most recent example: My new set of (nominal 30) Grand Bois Cypress measure 28mm on RR1.1 rims. My previous set measured 30.5 on the same rims. This is also borne out by measuring the bead-to-bead distance of old and new tires.
Still a nice tire, but much narrower (but the same weight!) than the old tire...

Similar story with the Pasela 32. Some in the past have been way narrow, more recent models tend to be larger again...

[nooneline]

Inflated tire size depends on some other variables outside the tire manufacturer's control - namely the rim width. If you have a rim width that leads to a lightbulb-shaped tire, it's going to measure taller but narrower than if you have a wider rim that leads to a more mushroom-shaped tire.

[tumbler]

Why aren't tires the size they say they are? Is it that hard to put a tire on a rim, measure it, and then write that size on the tire, or even just write in the detailed description the tires idiosyncrasies. Obviously tire size will depend on rim width some but that's fine, just list the description the tires real width on a rim of the manufacturers choosing. Anything would help.


I've done the same thing... ordered a set of "bigger" tires and ended up with smaller ones, particularly with Continentals. I agree that picking a common rim, Open Pro or something, and providing a measured size on that rim in the fine print would be helpful, even if the different manufacturers didn't use the same rim, so you could compare tire to tire within a manufacturer and make an educated guess as to how they would measure on your rims. Either that, or we should create a spreadsheet chart like the Weight Weenie kids do to compare measurements with different tire/rim combinations (maybe this already exists?).

[unterhausen]

I bought some bontrager 25mm a couple of years ago, bought the same model 28 this year. When I took the 25mm off, I compared the widths of the casing and they were identical. Haven't bothered measuring the tires on the rim, but they are small. Guess I should have bought the 30mm

[David Kirk]

Car and motorcycle tires are the same way - nominal.

The only wheel/tire stuff I ever bought based on size that has ever been spot-on are skateboard wheels. Everything else needs to be measured.

dave

[Tickdoc]

Just put the calipers away and hope there is clearance, Clarence.

I noticed my new favorite veloflex master 25's look suspiciously like 23's when I'm rolling. I guess I could measure, but they roll so good I don't really care.

[shovelhd]

Inflated tire size depends on some other variables outside the tire manufacturer's control - namely the rim width. If you have a rim width that leads to a lightbulb-shaped tire, it's going to measure taller but narrower than if you have a wider rim that leads to a more mushroom-shaped tire.

This.

[p nut]

Just put the calipers away and hope there is clearance, Clarence.

I noticed my new favorite veloflex master 25's look suspiciously like 23's when I'm rolling. I guess I could measure, but they roll so good I don't really care.

My Veloflex 700x25's were 23mm on the dot.

[PaulE]

I wear shoes anywhere from 10-1/2 to 11-1/2 or 43 to 45 depending on brand and type of shoe, my foot measure 10-1/2 D on all the shoe sizing devices in shoe stores. For shirts and jackets I am anywhere from medium to extra large. I think "relaxed fit" jeans are just larger jeans labeled with a smaller size. I fit in 34 inch waist relaxed fit jeans but find I need a 35 or 36 inch waist in dress pants.

Cycling clothing is the most infuriating, in bibshorts and jerseys I can be anywhere from medium to XXXL depending on the brand and then sometimes even within the same brand the sizing isn't consistent even when staying within race-cut vs. club/tourist cut.

And then there are thermometers. You can look at 5 of the same brand new thermometer sitting together on a shelf in the store and they can have 5 different temperatures.

Unless we're talking about precision parts, it seems that measures are approximate.

Sorry for the drift and rant, carry on.

[bicycletricycle]

right, clothing manufacturers should have to list the actual dimensions of the clothing. If all XL shirts can't be the same size (impossible to enforce) than at least list the pit to pit, sleeve length, etc.

same as the tires, I don't care that they are not what they say on the tire, I understand that they have manufacturing tolerances and that they are different on different rims. I just would like more real world info about the actual size of the tire, perhaps they could provide a place on their websites for people to post actual measurements of tire/rim combos.

The compass tire thing really blew my mind, Jan seems like an upfront guy, Why not just give some nuance in the tire description.

*tire will some a little small and then stretch up to size
*this tire tends to be oversized
*the new batch of these tires came in a little small

etc.



I wear shoes anywhere from 10-1/2 to 11-1/2 or 43 to 45 depending on brand and type of shoe, my foot measure 10-1/2 D on all the shoe sizing devices in shoe stores. For shirts and jackets I am anywhere from medium to extra large. I think "relaxed fit" jeans are just larger jeans labeled with a smaller size. I fit in 34 inch waist relaxed fit jeans but find I need a 35 or 36 inch waist in dress pants.

Cycling clothing is the most infuriating, in bibshorts and jerseys I can be anywhere from medium to XXXL depending on the brand and then sometimes even within the same brand the sizing isn't consistent even when staying within race-cut vs. club/tourist cut.

And then there are thermometers. You can look at 5 of the same brand new thermometer sitting together on a shelf in the store and they can have 5 different temperatures.

Unless we're talking about precision parts, it seems that measures are approximate.

Sorry for the drift and rant, carry on.

[beeatnik]

Just put the calipers away and hope there is clearance, Clarence.

I noticed my new favorite veloflex master 25's look suspiciously like 23's when I'm rolling. I guess I could measure, but they roll so good I don't really care.

Esto

Tire OCD or fetishism. Doods, if your bike was designed for 23s don't try to force a 25 which can measure anywhere from 23 to 28. One millimeter of clearance doesn't mean the bigger tire fits or will perform as intended. I got a CAAD10 (probably designed for a 23mm race tire) which fits 32s. I've got a C59 (probably designed for a 23mm race tire) which hardly clears a 25 inflated to 90psi. Through trial and error each bike rolls on the right tire.

On the other hand, if you've got a bika designed to fit 40s, how much difference in ride quality can be felt between a 28 and a 30? It's a wash, que no?

[donevwil]

It is perplexing and annoying. I recently bought a pair of Schwalbe Marathon Supremes advertised as 42s and listed by Schwalbe as 622 x 42. After receipt I look at the sidewall and it reads 622 x 40, mount them and they measure 36. These were intended to upsize my Compass Barlow Pass 38s that measure 37 mounted. So I bought a significantly larger tire that ended up being smaller. Marveloous !

[Mark McM]

right, clothing manufacturers should have to list the actual dimensions of the clothing. If all XL shirts can't be the same size (impossible to enforce) than at least list the pit to pit, sleeve length, etc.

I don't think this can work for clothing, either. Garments are not all designed to fit the same - some are meant to be loose, some are meant to be tighter, some are meant to drape a certain way, or to present a certain silhouette. So two different garments which are perfectly tailored for the same individual may have different actual fabric measurements.

And that's just for men's clothing - women's clothing adds whole new dimensions (literally and figuratively).

[bicycletricycle]

I don't think this can work for clothing, either. Garments are not all designed to fit the same - some are meant to be loose, some are meant to be tighter, some are meant to drape a certain way, or to present a certain silhouette. So two different garments which are perfectly tailored for the same individual may have different actual fabric measurements.

And that's just for men's clothing - women's clothing adds whole new dimensions (literally and figuratively).



I am not claiming that providing the actual dimensions of things (tires, clothing, etc) will necessarily prevent any surprises from occurring. However, it would be hard to argue that it would not help.

[bicycletricycle]

It is perplexing and annoying. I recently bought a pair of Schwalbe Marathon Supremes advertised as 42s and listed by Schwalbe as 622 x 42. After receipt I look at the sidewall and it reads 622 x 40, mount them and they measure 36. These were intended to upsize my Compass Barlow Pass 38s that measure 37 mounted. So I bought a significantly larger tire that ended up being smaller. Marveloous !

ya, I have some marathon supremes in 35s that seem to actually be 32s (on VO raid rims)

great tires otherwise, seem to be impossible to wear out.

[bicycletricycle]

I sent an inquiry to compass, they sent me a description of their practices as well as a link to this article by Jan from 2014

https://janheine.wordpress.com/2014/07/14/the-actual-width-of-tires/

basically it says that they make the tires undersized so that after break in and at max inflation they reach the labeled size. makes sense, that way if a bike has tight clearance the tire will never go over the size it says on it.

would be nice if the linked article was in the description of the tires.

[ultraman6970]

If the manufacturers don't lie (sometimes) they wont sell their stuff, specially in tires since looks like everybody but me are looking for like 50 mm wide tires now a days :P

[bicycletricycle]

oh man, ferocious burn.

If the manufacturers don't lie (sometimes) they wont sell their stuff, specially in tires since looks like everybody but me are looking for like 50 mm wide tires now a days :P

[happycampyer]

I sent an inquiry to compass, they sent me a description of their practices as well as a link to this article by Jan from 2014

https://janheine.wordpress.com/2014/07/14/the-actual-width-of-tires/

basically it says that they make the tires undersized so that after break in and at max inflation they reach the labeled size. makes sense, that way if a bike has tight clearance the tire will never go over the size it says on it.

would be nice if the linked article was in the description of the tires.That's very interesting. That's also consistent with my experience noted above. I suppose the more supple the casing, the more it will expand. Ime most tires change very little if at all over their life.