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VICG
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19 Posts
Discussion Starter #1
I would like to change the 37c (semi slick) tires that are on my Scott Sportster P6 hybrid to 30c (road) tires, can I still use the same tubes from the 37c tires?:confused:
 

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VICG
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19 Posts
Discussion Starter #3
Thanks

Thanks alot Industry_Hack I wasn't sure since I read somewhere on the net that if I were to use that size of tire I could use my old tube.:thumbsup:
 

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Total noob (& forum admin)
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12,350 Posts
Tubes are designed to fit a certain size tire when full expanded. Some tubes are designed to fit more than one size, like a 23-25, or 25-28, but that's only about a 10% difference, and that's usually a matter of the tube stretching a bit extra. Cramming that big tube into a smaller tire is a bad idea, as it won't be able to inflate to the proper shape.

For the record, I'm running a 25mm tube in a really fat 28mm tire, and I flatted. Patching doesn't work, because the tube stretches so much to fit, and the patch doesn't stretch.
 

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DX's Biggest Member
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Gotta come down on the other side of this one, Hack; the larger tubes oughta just have the opposite effect, be a little thicker fully inflated inside the smaller tire. Until I see otherwise, that's my story and I'm stickin' to it.
 

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Gotta come down on the other side of this one, Hack; the larger tubes oughta just have the opposite effect, be a little thicker fully inflated inside the smaller tire. Until I see otherwise, that's my story and I'm stickin' to it.
Uh, did you miss this part?

Cramming that big tube into a smaller tire is a bad idea, as it won't be able to inflate to the proper shape.
 

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DX's Biggest Member
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Quit stalking me, Heathcliff....

Hack, I'm basing it on my own experiences; YMMV. As will OP's. Now, DA, that's a whole 'nother can of worm-eaten peat moss; don't think he uses miles, kilometers, or kellicams, for that matter..........................
 

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tubeing

If the tube is larger than the tire, you run the risk of folds, or wrinkles. Also, the tube might not expand evenly, which is a factor in proper "bead" seating!
 

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We're only talking about the difference of going from 1 3/8 to 1 1/4, so I doubt that a change in tubes is actually required. Maybe the current tubes were stretching a bit to fit the larger tires and they'll fit the new tires perfectly!

Just to put it in perspective: When I go to the LBS for a tube for a 28x406 tire, nine times out of ten I'll get handed a 'dual' 406/451 tube, which in actuality two inches too big in diameter. Nobody seems to care except me. That's like handing someone a tube for 38x700C and telling them it's fine to use with their mountain bike. Compared to that, the 1/8" difference in width that you're talking about is less than meaningless.
 
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