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Thread: 25mm Tires ????

  1. #1
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    25mm Tires ????

    I just tried 25mm tires for the first time (conti GP4000) . When I got home from my first ride on them I realized I mounted them with 23mm tubes I always use . Should I have gotten size specific tubes (25mm) ??? I rode over 40 miles with these tubes , did I get lucky ? Or is there no need for a 25mm tube ??

    I really like 25mm . I don't seem any slower and there is a much smoother ride . I don't race ( or get over 25 miles an hour for that matter ) , so I believe I found my new tire width ...


  2. #2
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    23mm tubes are fine....no issues or worries at all
    Dave Hickey/ Fort Worth

    My 3Rensho Blog: http://vintage3rensholove.blogspot.com/

  3. #3
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    Most tubes are rated for something like 18-25c width. They are made in ranges, not one specific size.

  4. #4
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    the tubes I have are 18/23 thats why I asked

  5. #5
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    Just curious...can you measure your GP4Ks with a caliper to find the true width? My 23s seem to be more on the 21mm side of things...
    "They'll be making us a shoe made entirely of steel wool and canvas. Steel is real, wool is real, so it follows that steel wool is the realest material of them all."
    -buck-50

  6. #6
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    Nice Pegoretti!
    It's funny until someone gets hurt. Then it's hilarious.

  7. #7
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    Quote Originally Posted by PinarelloFan
    the tubes I have are 18/23 thats why I asked
    I've been running 18-23 tubes with 30mm cross tires. nothing has exploded yet. you should be fine running the above tubes with 25mm tires. don't Contis run slightly narrow anyway?

  8. #8
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    Quote Originally Posted by weiwentg
    I've been running 18-23 tubes with 30mm cross tires. nothing has exploded yet. you should be fine running the above tubes with 25mm tires. don't Contis run slightly narrow anyway?
    I use 26 inch mountain bike tubes on my 29er. Rubber expands fine. Granted it expands to a larger diameter better than a larger width, but still anything within reason shouldn't worry you.

  9. #9
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    Quote Originally Posted by Jim Nazium
    Nice Pegoretti!

    Here, here!

    It looks almost industrial with graffiti on it, beautiful bike.

  10. #10
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    Conti 25mm aren't much bigger (if at all) than other brand 23s.

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    Yea major compliments on the bike. Thats what I hope to someday own when I get enough cash.

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    Seem to be?

    Quote Originally Posted by MaestroXC
    Just curious...can you measure your GP4Ks with a caliper to find the true width? My 23s seem to be more on the 21mm side of things...
    How can something seem to be a given size? Either it is or it isn't. Is there some alternative to measuring that you're keeping to yourself? For me, Conti GP3K and GP4K have both always been 23.0 mm.

  13. #13
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    Quote Originally Posted by de.abeja
    Here, here!

    It looks almost industrial with graffiti on it, beautiful bike.
    Here a few closer shots of the "graffiti"


  14. #14
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    Quote Originally Posted by PinarelloFan
    I just tried 25mm tires for the first time (conti GP4000) . When I got home from my first ride on them I realized I mounted them with 23mm tubes I always use . Should I have gotten size specific tubes (25mm) ??? I rode over 40 miles with these tubes , did I get lucky ? Or is there no need for a 25mm tube ??
    Using a given sized tube on a larger cross section tire means that the tube will have to expand more when inflated. That results in a slightly thinner layer covering the high pressure air. So perhaps you give up a bit of flat protection. How often does a glass sliver, thorn, etc. only partially penetrate the tube?

    For 23 to 25, I'm suspect you'd never notice the difference caused by a slightly undersized tube. 23 to 28 is probably ok too. 23 to 32 might be pushing your luck.
    Hard work pays off in the future. Laziness pays off now.
    -- Steven Wright

  15. #15
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    I recently replaced some tires and tubes for a co-worker who had been riding with the original factory equipment for 15 years. The tires were worn to the threads but she had never had a flat. When I got into the 38mm tire, I found Trek had been using tubes rated for 23mm. I would agree there is some room for tolerance.

  16. #16
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    Quote Originally Posted by PinarelloFan
    I really like 25mm . I don't seem any slower and there is a much smoother ride . I don't race ( or get over 25 miles an hour for that matter ) , so I believe I found my new tire width ...
    [/URL]

    There was a thread on this somewhere, but I switched my front to 23c and I noticed the bike is a lot easier to handle with the narrower steering tire. It's violence upon the hands, but I can brace for that. Tire size made more of a difference than I anticipated. That frame is killer by the way.
    "Do I need to tell you what the f*ck you can do with an aluminum tube? ALUMINUM!"

  17. #17
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    25s are great -- 28s are better

    Like the OP, I was suprised at the difference in the ride when I went from 23s to 25s.

    I saw no downside -- only more comfort and a better grip on the road.

    Now on 28s (though they don't pump up that big -- more like 26.5). Love 'em.

  18. #18
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    Don't worry about the tubes in there - you could always carry spare 25 tubes and switch when yu get a flat.

    I used Ultra gator 25's on my steel nag and loved the ride and decided to use same for a new build I was doing eventhough it wasn't appropriate for the bikes racing pedigree and found it to be somewhat sluggish - will have to switch back to 23 on that bike to see if things change.
    A writer cannot serve today those who make history, he must serve those who are subject to it - history's victims ..... Albert Camus

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