himespau 

So I'm looking for some new tubes and am having a hard time finding tubes that are exactly the size of my tires. I'm getting new 26x1.35 tires and am in need of new tubes (am out of spares). Most tubes I see are either 26x1-1.25 or 26x1.5-1.75 (or larger) and I don't see (at least in the cheap tires and am not convinced that expensive tires are any better) any that cover the 1.35" range. Is it better to get tubes that are a little too big or a little too small? I thought I read somewhere that a little too big was better, but I can't find that now.

bobotech

I think the main reason why you want to keep the proper range is because when installing a tube that is too big, you run the risk of a pinch flat and it makes it a nightmare to install. All that extra rubber inside the tire makes it hard to stretch the tire over the rim especially if you have a very thin tire. I remember I had a tube for a 700c 32-38mm tire and was using it for a 700c 25mm tire. I had such a hard time getting the tire to pop over the rim that I ended up breaking a steel reinforced tire tool. Went to the bike shop and the guy there sold me a tube for a 700c 18-25mm tire and was able to pop the tire over the rim with his hands.

Not sure about using a tube that is too small, I imagine that the tube might burst easier due to stretching more?

Retro Grouch 

Given that choice I'll pick the slightly too small tube every time.

FBinNY 

There's no easy answer because there's so little correlation between the nominal size written on the box, and the actual size of the tube.

I prefer to use the largest possible tube that's smaller than the tire (actual size) when unstretched. IME stretching less on inflation means thicker material, so natural air bleed is a bit slower, and the tube is marginally more flat resistant.

Since you really cannot rely on the box dimension you might want to measure the tube itself. My rule of thumb is to look for a tube who's width when flat is very close to the width of the tire it's going into. Since the flat width is 1.5x the diameter, this allows for a little stretch on inflation, and gives me the predictability of not relying on very unpredictable box markings.

AlbertaBeef

My experience is too-small tubes result in more flats. I've tried running 700x23c tubes in 700x28c tires and had more punctures as well as failures where the tube meets the valve stem.

If you can find a decent 26x1.5 that fits inside well, that's what I'd use. FYI I have some Ritchey Tom Slick 1.4's on my commuting MTB, and I use 1.5/1.75" tubes in it...

I find that the smaller 26x1/1.25 tubes are REALLY small and light, and just don't hold up.

himespau 

That was sort of my fear. I figured slightly larger would mean thicker tubing, but the pinch flat thing didn't occur to me. Then I found some for $.50 more than covered the nominal size of my tire, so I might just go with those and hope that the measurements of both the tube and the tire match what they say they're going to be.

calstar 

Fortunately not my experience(40yrs of continuous cycling). I always run a little smaller tube(never larger for reasons stated above) and never have had tube/valve stem issues; I do use the threaded nut that comes with the prestas. I don't get many flats in general, and when I do its almost always thorn, wire, etc. I doubt if I get more flats than typical(whatever that means) but can't compare the two since I don't ride the larger.

Brian

fietsbob

thin tubes get thinner as they are inflated to fill a fatter tire,, so weep air faster.

live in-person opening the box the inner-tube comes in,
and adding a bit of air to round it out , and trying it
will be so much more useful,
than multiple opinions offered.. mine included.

jim hughes

There are probably too many variables involved for a definitive answer.

Flying Merkel

I used a too-large tube. The tube creased and rubbed against itself, cause tube fail. I'd go with one size too small.

rekmeyata

I'm another small tube person. Smaller tubes are easier to install tires with, their a tiny bit lighter in weight as a bonus. As a con the thinner tube being stretched a bit more will bleed air a wee bit faster, and a larger tube is just a tiny bit more resistant to flats, but this a moot point since you should be topping off your air before every ride anyways, so you may have to put in 2 or 3 pounds more air...big deal. But all these tiny bits here and tiny bits there are just that...tiny, non noticeable, what you will notice the most is the ease of installing a tire vs using a slightly larger tube.

I'm another 40 plus year vet and I too have always used a size smaller tube. If you want a thorn resistant tube then don't do it by going with a size larger because the effect against flats is almost nil, rather get a thorn resistant tube, these tubes are quite a bit thicker at the area where the tube contacts the tread then a normal tube...but their also quite a bit heavier if that matters. Sunlite probably makes the best thorn resistant tube.

However, if flats are causing you headaches thorn resistant tube is not the best place to start. The best place to start is with the tires. Some tires like the Specialized Armadillo will stop almost anything, but no tire is flat proof.

AlbertaBeef

I think my issue with flatting more is that as a 225-230lb clydesdale, I'm more-easily susceptible to pinch flats and flats from road debris, especially with a thinner/stretched-out tube. It won't necessarily be a lighter-weight riders' experience, but has been mine.

CACycling

I'm at least your weight and ran 700 x 23 tubes in 700 x 28 tires on my commuter for several years with no issues. I've yet to get a pinch flat on any of my bikes (even though I routinely bomb over RR tracks on my commute) and flats are rare in general. Proper inflation and staying out of the gutter are key to avoiding many tire problems.

Al1943

Yep, smaller is better. Wrinkles are bad.

rekmeyata

smaller tube will not pinch flat under more weight, that problem is caused by too low of air pressure for the weight being carried. If your running 23's and your pinch flatting with the tires at max rated psi then that should be telling you something...move up to a 25 at least and probably a 28 to be safe.

Kimmo

If the lightly-inflated tube doesn't fit properly inside the tyre, forget it. You'll probably get away with a tube that's a bit too small.

Paul Barnard

Or you could just order the correct size.

https://www.google.com/search?q=26x1...w=1348&bih=605

pinchflattire

i have a front tube to replace

700x32c and i can find only 25 up to 28c or 35c up to 42 c (schrader)

SethAZ 

When I thought I was going to be running 28s on my new bike I ordered some more tubes in the 25-28mm size (I needed more tubes anyway). I ended up getting some 32mm tires, and just used the 25-28mm-labeled tubes. When I eventually run out of these tubes I'll look around for ones more appropriately sized, but in the meantime it's not something that keeps me up at night.

Crankycrank

Do a google search. Plenty of tubes in the size you need available unless you're buying from the LBS and that's all they have in stock.

tyrion

Either will work. The smaller tube will be lighter with a thinner wall (when inflated in a 32mm tire), the bigger tube will heavier with a thicker wall. Personally I don't care about the lighter weight so I'd go with the bigger tube.

xenologer

Smaller for weight savings but more frequent inflation and flat risk

Bigger or 'thorn resistant' (thick tubes) for problem customers who keep coming back every month for 'flat tires' that clearly have never been inflated.
-just have to be careful on install not to fold or pinch the extra rubber

pinchflattire

thank you for replys

the only downside for me in case of bigger tube is to get it into the tire with the rubber lean inside it

it is not the weight differential , as my bike is not racing light bike but a mixture between racing and street bike

so i'll get the 35 and hope it works

SkyDog75

Like Crankycrank pointed out, tubes in your desired size are out there and easy to find. Niagara Cycle's web site lists 19 different schrader valve tubes whose listed size includes 32 mm.

...but the difference between 32 and 35 mm is minimal. You're unlikely to run into any problems with a 35 mm tube in a 32 mm tire.