a question on tire width...

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rst72
Posts: 33
Joined: Mon Oct 05, 2015 3:19 pm

by rst72

I see charts that state a difference between a 23 and 25 is 18% in air volume. So, if a 23mm tire measures 25mm, is the air volume equal to a 25 that measures 25mm?

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fa63
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Location: Atlanta, GA, US

by fa63

rst72 wrote:I see charts that state a difference between a 23 and 25 is 18% in air volume. So, if a 23mm tire measures 25mm, is the air volume equal to a 25 that measures 25mm?

Volume is a function of width and height, so if the height is the same, then yes. But I believe a wide rim affects the tire height as well.

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pdlpsher1
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by pdlpsher1

I have the HED Belgium rims with an internal width of 20.5mm. When I put a 25mm Conti GP 4000 II tire on it balloons to 30mm wide. The height grows as well. The same tire on a rim with a 17mm internal width only measures 27mm wide. The wider rim increases the internal tire volume so much that I had to use a 100g standard tube. The 77g lightweight tube expands so much that holes started to appear in the tube with nothing external puncturing the tube. I think one reason that wide rim/tire rolls so well is that the tube is stretched so thin, hence rolling resistance is decreased. And of course the tire's contact patch changes and that helps too. I'm a huge fan of wider rim/tire.


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rst72
Posts: 33
Joined: Mon Oct 05, 2015 3:19 pm

by rst72

I have hed Belgiums as well. Paired with 25 vittoria open paves and then switched to the new open corsas. 25 open corsas did not work, so sized down to 23s. 23s would rub very slightly at times where as the 25 open paves would not.

I never measured the open pave width and height...I may have on old one that I should throw on to compare.

Marin
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by Marin

Side note, I have used 55g supersonic tubes in 35mm CX tires and I regularly run 65g R-Air tubes in 32mm road tires without holes appearing.

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pdlpsher1
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Location: CO

by pdlpsher1

Marin wrote:Side note, I have used 55g supersonic tubes in 35mm CX tires and I regularly run 65g R-Air tubes in 32mm road tires without holes appearing.


My problem could be unique however when I put an inflated tube in the sink to find a leak, I saw a row of pinholes in a line about two inches in length. The same thing happened on a different tube. I have no clue what made those holes appear. The tube is the Michelin lite tubes at 77g a piece. I did run very high pressure on them (120psi) but I have since lowered it to 100psi. This is on a tandem bicycle.


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Marin
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Location: Vienna Austria

by Marin

Strange, did you check the tire and rim in the area where the holes appear?

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Pepsi
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Location: Slovenia, Europe

by Pepsi

Can i mount 25 mm tire on my 2014 Mavic R-SYS ?


alcatraz
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by alcatraz

pdlpsher1 wrote:
Thu Jul 14, 2016 12:36 am
Marin wrote:Side note, I have used 55g supersonic tubes in 35mm CX tires and I regularly run 65g R-Air tubes in 32mm road tires without holes appearing.
My problem could be unique however when I put an inflated tube in the sink to find a leak, I saw a row of pinholes in a line about two inches in length. The same thing happened on a different tube. I have no clue what made those holes appear. The tube is the Michelin lite tubes at 77g a piece. I did run very high pressure on them (120psi) but I have since lowered it to 100psi. This is on a tandem bicycle.


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Check the position of that row of holes. What direction do they face and how far away from the valve are they?

Compare the two tubes. I'd be surprised if they weren't in the same position.

Run your fingers on the inside of the rim. Dremel sharp edges away.

I once had a new tire that always punctured my thin latex tubes upon inflation. I took it off 5 times and couldn't find what was causing it. Always puncture in the same place and always nothing there upon inspection.

It felt like a C.S.I. episode.

I ended up shelving the tire. I will reuse it but I have to put a thin patch over the spot causing punctures. If you got a 2 inch strip of holes, this solution isn't for you. Tried a different tire?

/a

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pdlpsher1
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Location: CO

by pdlpsher1

I have found that pinhole leaks in a tube (i.e. not caused by by a puncture) is related to tire pressure and tire volume. I was running too high of a pressure for the large tire size (actual width = 30mm). Now I only run 100psi on the rear tandem tire and with 77g lightweight tube I don't get any pinhole leaks anymore.

alcatraz
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by alcatraz

Thing is, most tubes are rated up to 28. 30 is right there and it sounds improbable that the limit really is at 28.

32-35 even as seen by a poster is actually ok.

Maybe it's a combination of size and pressure. I'd try a different tube (lighter even) and hope it's more flexible.

If it is the case that you are on the limit, aging the tube won't do you any good as the next tear'll come closer and closer as it hardens. One more reason to try different tubes.

Another thing that came to me is the tire maybe isn't designed for 120psi. It is after all quite wide. Maybe something happens to a lower pressure tire when it is pumped up high.

/a

by Weenie


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