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View Full Version : The Nice Thing About Standards (tire whine)


cachagua
08-09-2016, 01:54 AM
I wish there were a way to compare the size of tires without having to actually buy them, and put 'em on your wheels, and pump 'em up. A way you could know in advance if a given tire was the size you want.

Imagine if there were, like, a numerical scale. Some common measuring unit -- say, millimeters. I know, I know, this sounds wild and far-fetched, but hear me out: they could put numbers on the side of the tire, can you dig it? Saying how big, and if you knew the numbers, you'd know if the tire was bigger or smaller than some other tire, and if you could use it on your bike. Wouldn't that be a fantastic innovation? Wouldn't it be useful?

Here's a Compass 700x35 and a Challenge 700x38 next to each other. The former measures 37.8mm wide; the latter, 36.4mm.

https://67.media.tumblr.com/452ad8c10bcf22c9cfa244ea6c736fb3/tumblr_obmpiiQ0hk1tg04h3o1_540.jpg

The difference is subtle in the photo (although it's readily visible in person), and after all it's only 1.2mm. That's less than half of the difference the manufacturers say there should be. Except it's the opposite way -- the tire that's supposed to be larger, is smaller. Have another look:

https://66.media.tumblr.com/1a7b3a2de61192c2345d5564efe46d03/tumblr_obmpjhZtVe1tg04h3o1_540.jpg

Neither one's a bad tire. Neither one doesn't fit. I'll probably use them both. But I would really like to buy tires with a little more confidence! I feel like I'm playing tire piƱata -- blindfold me, give me a stick, and I'll spin around three times and buy whichever tire I whack. "Fit, Schmitt!" the manufacturers seem to say, "They're all rubber, what's the big deal?" Well, if you're really trying to craft your bike, maybe you get to be a little particular. Maybe your bike is a place to put your obsessive-compulsive tendencies, a place to be maniacal about details, so that you can take it gracefully when, in so many other situations in life, you don't get to control things. Would a little help, a little understanding from the manufacturers, on whom we depend for so much, be completely out of line?

Actually, it's okay. It just means I can keep on looking for more tires. I've searched and shopped for tires for so long now, it's become such a habit, that if I stopped doing it -- what would I do with the time? Geez, I might find myself so idle that I'd have to... ride my bike.

Unthinkable.

Stephen2014
08-09-2016, 05:17 AM
Checkout the ETRTO number, e.g. 28-622 will always the same whether the maker calls it 700x25c to make it seem lighter or they use the real size of 700x28c.

oldpotatoe
08-09-2016, 06:29 AM
Checkout the ETRTO number, e.g. 28-622 will always the same whether the maker calls it 700x25c to make it seem lighter or they use the real size of 700x28c.

Cept, look at the tire..the Challenge ETRTO number says 38-622..

Stephen2014
08-09-2016, 06:41 AM
Fair enough! I can't see it clearly enough to read it on my tablet.

AngryScientist
08-09-2016, 06:45 AM
to add to the confusion, a number of tires do "stretch" and may increase in width over time, so if you're at the limit when first mounted, you could be in for trouble down the road.

also - as we all know, final tire width is also dependent on the rim.

kittytrail
08-09-2016, 12:06 PM
there is/was a proposal called dDDirect (http://www.wheelfanatyk.com/store/rim-tire-measure-tool/) a few years ago but it seems like it didn't really had any, err, traction marketing-wise... :(

kinda nice though.

cachagua
08-09-2016, 12:34 PM
"This is a critical industry challenge, largely ignored at the present"... yeah!

I'd forgotten there was that tool. Seen 'em, haven't actually used one. I guess they only save the step of mounting and inflating, once you have the tire in your hands, but still -- an improvement.

2metalhips
08-10-2016, 06:06 PM
I've been using the Challenge 120 tpi GG's for 2 years now, for me they measure a true 38 mm on Stan's Iron Cross rims. The Riding Gravel website also measures 38. Really nice tires.

Ken Robb
08-10-2016, 07:50 PM
I have noticed that some tires that seem narrower than their official size would suggest are taller than some tires that measure the same width. For instance i had 700x28 Paselas that only measured about 25mm wide on Open Pro rims but they were taller than 700x25 Continentals. So I wonder, as far as the relative cushiness of the ride is concerned, if the measured width matters if the tire/tube volume is similar. Obviously the cross section shape matters when trying to determine if we can fit a tire on our bikes. Sometimes the critical dimension for fork clearance is width and sometimes it is height. I had a fork with plenty of side clearance but the top of some tires rubbed on the underside of the fork.

I no longer have this problem because all my forks now clear tires 32mm or more--much more on my Riv Allrounder. :beer:

cachagua
08-10-2016, 10:36 PM
...Been using the Challenge 120 tpi GG's for 2 years now... Really nice tires.

Totally looking forward to riding these. Just have to find a place where they'll really be at home. I have a giant park next door to me, lived here 6 or 8 years and I still get lost in there. But I'm only allowed to ride on pavement. I know a beautiful, idyllic former rail bed that leads back to a lake in deep wilderness, views, swimming, seen bears and cougars and eagles back there, dreamlike riding... it's 50 miles in the car each way. I don't have time for that.

I have noticed that some tires... are taller than [other] tires that measure the same width. For instance i had 700x28 Paselas that only measured about 25mm wide on Open Pro rims but they were taller than 700x25 Continentals...

This is something I don't completely understand. The naive view would be that the carcass of the tire inflates to a round section, no matter what -- and yet, some tires do seem to take an egg-shaped -- uh -- shape. Maybe they goop the rubber on thicker around the, as it were, equator of the tire?

Ken Robb
08-11-2016, 09:29 AM
I think the carcass can be designed to be more flexible neat the bead than under the tread (especially on tires with belts) and there is certainly more rubber under the tread than on the sidewall so I can imagine tires with similar volume assuming different shapes when inflated.

Davist
08-11-2016, 10:14 AM
agreed on the some are "taller" (in my experience, Continental), some are "wide" (Michelin), some are small (Vittoria) and some are just big all over (Schwalbe)

My experience with 25-28C on narrow (Shimano c24) and wide rims (Archetypes)

My CAAD10 doesn't care, BUT my Supersix EVO sure does.. Need one of the new ones..

I wonder if it would matter if they published the bead to bead width or something in addition to the ETRTO value?