18/25 tube with 28mm tire ok?

[bianchi10]

Just got new 28mm tires. All my spares and current inner tubes are 18/25. Whats your thought on using those tubes? Or should i size up to something like specialized 20/28 inner tube?

[Jaybee]

They are fine. Tubes are super stretchy.

[brewsmith]

From what I understand that is typically fine, and with higher quality, lighter tubes you can push the limit even further. For instance, the schwalbe ultralight 26" tubes are often used on 650b wheels with no issue. As long as the butyl extrusion is even and of good quality, you should be good.

Not that this is a recommendation, but I am currently running 28c Schwalbe ultralights on 38c Compass tires with no issue for the first several hundred miles.....

[David Kirk]

When I was a kid racing BMX we'd take 16" tubes and stretch them onto 20" wheels and blow them up and hope they didn't blow. If they lasted a few minutes they seems to hold on for some time.

Later in life we'd take 700c latex tubes and put them in 26 x 2.1" mountain bike tires. You'd stand back when inflating them because a reasonable number would let go before you were finished pumping them up.....but the few that didn't sure were light!


dave

[charliedid]

I'm gonna be the guy that says no. The ratings are not exactly arbitrary and the fact that they "stretch alot" doesn't mean you should stretch them alot and then ride them.

[cmbicycles]

Take a tube and inflate it out of the tire to see how much it stretches. You will be fine to use in a 28.

I just pulled a 20" tube out of my daughter's 26" wheel mountain bike this past weekend when she flatted... 20+ thorns pulled out of the tire, couldn't find the hole in the tube, but put a right sized tube in. I got the bike second hand so it came to me that way and she's been riding it for about a year with no issues.

[jtbadge]

A tube one "size" below the tire you're running is going to be fine. I have always run 28-32mm tubes in 40c tires, and often run 20-25mm tubes in 28c tires, whatever's around.

That said, running a tube sized larger than your tire doesn't make as much sense.

[berserk87]

Great topic. I had this conversation with a friend recently. Our collective answer was a mutual shoulder shrug. Thanks for the comments and insight.

[jtakeda]

Youll be totally fine.

I run 1.5x26'' tires in my 650b bike because 650bx38 tubes are really expensive/hard to find at a shop