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Hepmike
10-01-2014, 12:46 PM
I find myself in a probably not-so-unique situation- different size tires on front/back (23cc vs. 25cc) and my saddle bag only fits one spare.

A lot of replacements tend to run 18-23cc, and then a larger version- so either way i'm either running something slightly too small for my back, or if i carry something larger for the back- slightly too large for my front.

So the question is- would it/should it make any diff? Better to run too small, or too large for a given tire? This might be a really dumb question, but somehow I believe there is a logical, semi-scientific answer that will enlighten me...

AngryScientist
10-01-2014, 12:59 PM
smaller is better in your case.

fwiw, i use 23c tubes in 33c fatties all the time.

the issue is trying to jam a tube that is too BIG into a smaller volume tire.

dave thompson
10-01-2014, 01:47 PM
Different brands of tubes carry different size designations. I've found some that are labeled for both 23 & 25.

Vinci
10-01-2014, 02:06 PM
I use 18-23 size tubes in everything up to 28mm.

Tubes stretch a lot and will be fine in your scenario.

palincss
10-01-2014, 04:29 PM
I find myself in a probably not-so-unique situation- different size tires on front/back (23cc vs. 25cc) and my saddle bag only fits one spare.

A lot of replacements tend to run 18-23cc, and then a larger version- so either way i'm either running something slightly too small for my back, or if i carry something larger for the back- slightly too large for my front.

So the question is- would it/should it make any diff? Better to run too small, or too large for a given tire? This might be a really dumb question, but somehow I believe there is a logical, semi-scientific answer that will enlighten me...

Those tubes you're considering do not come in 18-23 cubic centimeter size. It's width they're measuring, and they do it in millimeters. The abbreviation for millimeters is "mm".

carpediemracing
10-02-2014, 08:26 AM
When I was being a weight weenie I put smaller tubes into larger tires (or if I only had the narrow tubes left). I had a lot of flats. I can't explain but I imagine that the overly stretched tubes are more vulnerable to any kind of damage.

We're talking some road tubes (I think they used to come in really narrow sizes, maybe up to 20c tube stuck inside a 23c tire) as well as mismatches in mtb tubes (like tubes rated to 1.25" in a 1.5" tire, or 1.5" tubes in a 1.9" tire).

Also, as a shop, if we ran out of tubes, we initially put smaller tubes in tires. After bunch of "hey this went flat again" we went to larger tubes in a given tire. No more return customers.

No explanation, just my own experience with maybe 10-15 tube installs for my own wheels and maybe 20 customers' tires/tubes.

All the above with butyl or some discontinued not-very-stretchy tube that I think sold under the Panaracer brand. It resembled a semi-clear semi-soft plastic.

MeatPuppet
10-02-2014, 12:51 PM
Continental race tubes run 700 x 20-25, I've used them in 23s and 25s, no difference I could tell aside from having to be a bit more careful about making sure tube gets pinched by the tire when installing on a 23.

p nut
10-02-2014, 01:19 PM
I have used 18-23 tubes in 28 tires without issues. However, I did notice that it loses air quicker than the proper-sized tubes.

pcxmbfj
10-02-2014, 02:39 PM
When I was being a weight weenie I put smaller tubes into larger tires (or if I only had the narrow tubes left). I had a lot of flats. I can't explain but I imagine that the overly stretched tubes are more vulnerable to any kind of damage.

We're talking some road tubes (I think they used to come in really narrow sizes, maybe up to 20c tube stuck inside a 23c tire) as well as mismatches in mtb tubes (like tubes rated to 1.25" in a 1.5" tire, or 1.5" tubes in a 1.9" tire).

Also, as a shop, if we ran out of tubes, we initially put smaller tubes in tires. After bunch of "hey this went flat again" we went to larger tubes in a given tire. No more return customers.

No explanation, just my own experience with maybe 10-15 tube installs for my own wheels and maybe 20 customers' tires/tubes.

All the above with butyl or some discontinued not-very-stretchy tube that I think sold under the Panaracer brand. It resembled a semi-clear semi-soft plastic.

When I went to 29r wheels I used 700x35 and had flats with every tube so now use 26x2" or wider.
Also in 650b.

JayBay
10-03-2014, 09:50 AM
A couple weeks ago when I ran out of tubes on a cross ride I tried a 20-23 road tube in my fairly voluminous cross tire (700x33 Clement LAS). I don't know if the road tube was old, or just real thin, but it would NOT stretch out far enough to fill the inside of the tire, and at full pressure I still had spots where the tire was literally flopping around as the tube wasn't pressing against it. I made it out of the woods and about a mile down the road, felt like I was riding on an egg. Then the seam on the tube exploded. Bigger = better.

Admiral Ackbar
10-03-2014, 02:26 PM
I've used 19-25 and 18-23 tubes in tires as big as 28 and 32mm .... no problems for me. they might seep air a bit faster? but i run low psi so its a non issue for me. also makes mounting tires/tubes a bit easier imo, less tube to get in the way or stuck under the tire bead.

they're also lighter, if thats a concern.

ymmv atmo atmo atmo etc etc.