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  1. #1
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    What is the O.D. of Continental's Race King 29er Tires

    According to Continental's web site, both of their Race King 29er tires (29 x 2.0 and 29 x 2.2) have an outside diameter of 28". Can anybody verify this or post the circumference of their Race King tire using a cloth tape. I would like to put larger 29er tires on my Specialized Crosstrail mountain hybrid, which has about 1/2"+ clearance between the FD (front derailleur) linkage and its current 700 x 38 commuter tire (27 1/2" OD).

    If the 28" O.D. is a misprint then does anybody know of a 29 x 2.0 XC tire that has an O.D. of 28". I have read that most 29er tires have an outside diameter of 28 1/2".

  2. #2
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    I have the Continental Mountain King, just measured it to program my computer, came out to 88.5 inches or 2248 mm. This is the circumference, not the OD, hope this helps.
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  3. #3
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by bwalton
    According to Continental's web site, both of their Race King 29er tires (29 x 2.0 and 29 x 2.2) have an outside diameter of 28". Can anybody verify this or post the circumference of their Race King tire using a cloth tape. I would like to put larger 29er tires on my Specialized Crosstrail mountain hybrid, which has about 1/2"+ clearance between the FD (front derailleur) linkage and its current 700 x 38 commuter tire (27 1/2" OD).

    If the 28" O.D. is a misprint then does anybody know of a 29 x 2.0 XC tire that has an O.D. of 28". I have read that most 29er tires have an outside diameter of 28 1/2".
    "Most" 29er tires have an OD of just over 29" (~740mm).

    28" is the nominal diameter many euro companies use for any 700c tire wider than ~44mm.
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  4. #4
    Plays with tools
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    28" refers to the bead seat diameter not the OD of the actual tire. You could think of that 28" as the ID for the tire or OD for the rim, sort of at least.

  5. #5
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    Quote Originally Posted by customfab
    28" refers to the bead seat diameter not the OD of the actual tire. You could think of that 28" as the ID for the tire or OD for the rim, sort of at least.
    That doesn't sound right. 700c wheels have a bead seat diameter of 622mm, which is about 24.5"

  6. #6
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    Conti just refer to their 29er tyres and tubes as 28" sometimes. The tyre says 29er in big letters on the side though.

    The Race King 2.2 is 740mm outside dia, the 2.0 is about 15mm less.

  7. #7
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    Quote Originally Posted by boomn
    That doesn't sound right. 700c wheels have a bead seat diameter of 622mm, which is about 24.5"
    Well that is certainly what that number references. Nominal tire sizes have never matched up to there actual measurement. 700c is pretty comes out to 27.5, kind of close to 28". For some reason you see road tubulars marked as 28" frequently.

  8. #8
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    Using Grizzlyplumber's circumference measurement of 88 1/2", the outside diameter of a Mountain King 29er tire is 28 3/16".

    (Grizzlyplumber what is the width of your Mountain King 29er tire that you measured? 2.0 (50mm) or 2.2 (55mm)?)

    I have read that Europeans refer to 29ers as 28ers because the actual O.D. of the average 700 x 50 and 700 x 55 mountain bike tire around 28".

    Having said that, I measured the circumference of a Specialized 29 x 2.0 Captain Control Tire a few months ago and the O.D. worked out to be a little bit over 29". These Captains 29er tire are really tall.

    Apparently there is no industry standard for tire height. Like I mentioned in my first post, the Specialized 700 x 38 (29 x 1.5) Cross Road commuting tires have an O.D. of 27 1/2+". The Specialized 700 x 47 (29 x 1.85) OEM Borough Sport XC tires that came on my Crosstrail Hybrid measured out to roughly 27" O.D..

  9. #9
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    There certainly is a lot of variation but like shiggy said, most 700c tires that qualify as MTB tires are over 29" in diameter. Shiggy's measurement of 29er tires on this page show that most are at least 370mm from axle to the tallest tread point, which works out to 29.13". I've measured most of the 29er tires I've had and they all came out over 29" as well

  10. #10
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    According to Boomn's link the 29 x 2.2 Race King has an ourside radius of 370mm, which works out to be 29 1/8" O.D..

  11. #11
    CB2
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    Quote Originally Posted by bwalton
    According to Boomn's link the 29 x 2.2 Race King has an ourside radius of 370mm, which works out to be 29 1/8" O.D..
    That sounds about right.

    You bastards piqued my interest enough to get off my a$$ and go down to the basement and measure mine.

    Unweighted radius of my RK 2.2 is 14.625" or a diameter of 29.25"

    While I was at it I measured the Crossmark on the back too; 14.375" or a diameter of 28.75"

  12. #12
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    Quote Originally Posted by customfab
    Well that is certainly what that number references. Nominal tire sizes have never matched up to there actual measurement. 700c is pretty comes out to 27.5, kind of close to 28". For some reason you see road tubulars marked as 28" frequently.
    28" does not reference bead seat diameter, nor does any other nominal tire size.
    all nominal tire sizes (e.g., 24", 26", 27", 650, 28", 700, 29er) refer to the approximate (hence, nominal, meaning in name only) OD of the tire. that's the reason why some tires of the same nominal size have different ISO sizes. ISO sizes are based on bead seat diameter to ensure compatibility.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

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