Fat tire, narrow rim

Discussion in 'HOW TO' started by Psychographic, Oct 8, 2019.

  1. Psychographic

    Psychographic

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    I'm looking to exaggerate the size between a front and rear 20" tire. I plan to use a 1" front tire, and wondering if a 4" fat tire would fit on a 1" rim.
     
  2. kingfish254

    kingfish254 CHECK OUT MY SALE THREAD FOR COOL STUFF! Pro Member

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    I believe it will. I remember a few RRBers putting the OCC 20x4 tires on a regular 20" rim before. It was about 6 years ago or so.
     
  3. Starnger

    Starnger

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    As long as ISO rim diameter is same, it surely will fit! But the deal is that not any combination would be safe to ride. When running too narrow tire on too wide rim you are wearing it too intensely and risking having a rapture and blowout. And when running to wide tire on too narrow rim you are risking that it would unbalance itself on the turn. The deeper inner tube can sit in the rim, the more stable it is. You can model yourself the situation in your mind. Applying force on your wheel axle direction can lead to your tire with inner tube just slipping out of the rim edge. So, for a show bike that would mostly go slow and straight it would be a rather safe option to go for. If you are planning to actually ride the bike often and fast, tilt it in the turns or attack curbs with it, then i'd rather not risk using such a combo. There are plenty of wide rims for 20", you can try those, or lace two rims in one hub for example.
     
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  4. Psychographic

    Psychographic

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    I am building a bike just to cruise around at shows and such, so cornering is not a problem. I was curious about the possibility for the tire to roll over during a turn, now I know.
     
  5. clamdigger

    clamdigger

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    A lot depends on bead and sidewall construction of the tire , and the profile / bead seat area of the rim. So there is no direct answer. The safe , general advice that I frequently read is that the ratio of max tire width to rim width is 3 to 1 .
     
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  6. papawrandy

    papawrandy

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    Not trying to hi jack this tread but I was wondering about this also. I got a 20” bike out of a dumpster at work with a 2.8 tire on a freewheel rim. It has no brake components so I was wondering about mounting it on a coaster brake rim. What size is safe to use? It’s a beater bike for my grandson. Thanks
     
  7. Klunkruiser

    Klunkruiser

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    Ideally, I think a tire that wide is best on a rim that measures 30mm+ on the inside. Closer to 35mm is better.
    But I know that they have been mounted on narrower rims with varying degrees of success.

    As mentioned above somewhere, a lot will depend on rider weight and the aggression with which the bike is ridden.
     
    MattiThundrrr and papawrandy like this.

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