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Thread: Radial tires on a 1987 K75S

  1. #1
    am48@mail.com
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    Radial tires on a 1987 K75S

    Time to re-tire my bike and I'm thinking of going with slightly smaller sizes in order to mount radials. But, I'm wondering: Has anyone tried this yet and, if so, what was the outcome?

  2. #2
    Registered User WalterK75's Avatar
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    The general recommendation for the K75 is to stick with the bias tires for which the bike was designed. The new bias tires are better than those available when the bike was manufactured. Michelin Activ is the one I'm using and it's more than capable of handling my riding style and the roads on which I ride. Granted I'm not an aggressive rider.
    Walter

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    I don't have a K75, but I have been running radials on my 1990 K1 forever. What is the concern? Does the K75 not run with radials? What are the design features that require a bias ply tire?

  4. #4
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by EMSimon View Post
    I don't have a K75, but I have been running radials on my 1990 K1 forever. What is the concern? Does the K75 not run with radials? What are the design features that require a bias ply tire?
    Actually - I don't think there are any "design features" except matching the correct size tire to the rims available. I had radials on THE K75S - but it had rims (polished 3 spoke) off a special edition ('87?) K100RS - which came with radials. The tires were low profile wide tires. This required modifying the centerstand to clear the rear rim, and made R&R of either wheel a PITA (rear - the exhaust had to come off to clear the brake caliper.) The rear also ran offset about 3/4" to the left of centerline of the bike due to the different offset on the K100RS rim (and the need for the tire to clear the swingarm.)

    The bike handled just fine.. Never felt the offset - the bike tracked straight and true. Only thing I noticed was one side of the rear wore faster than the other, but that's also true even without the offset on most K bikes (left side usually.) There is nothing different in suspension between that designed for radials and bias-ply..
    Don Eilenberger http://www.eilenberger.net
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    Quote Originally Posted by am48@mail.com View Post
    Time to re-tire my bike and I'm thinking of going with slightly smaller sizes in order to mount radials. But, I'm wondering: Has anyone tried this yet and, if so, what was the outcome?
    First: Welcome to the Forum!

    What, specifically, are you trying to accomplish? What are the characteristics that are important to you? Are you not able to achieve these with bias-ply tires? In most cases, a radial tire of the same diameter as your current tires requires a wider rim than is currently on your bike.

    On another subject, what is the last 3 numbers of the VIN on your 1st year (US) S? Is it one of the Red Metallic, Black, or Columbia Silvers ones? I kinda have a "thing" for K75Ss (actually have 4 of them even though my sig line says 3). One of mine was built on the second day of production of the '87 US spec K75Ss (May 16, 1986).


    LONG MAY YOUR BRICK FLY!

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  6. #6
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    I run radials consisting Avon AV46 140/80-17 on rear and Bridgestone BT-023 110/80-18 on front of a 93 K75S with no clearance problems and fit on the narrower K snowflake rims just fine.


    The handling and ride is better than bias ply. I also think the tires stick to the road better in wet conditions.

    Just my opinion.

  7. #7
    keither
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    k75 tires

    My opinion; get newest Michelins radials in stock size. Works for me.

  8. #8
    am48@mail.com
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    Thanks to all for the warm welcome, advice, tips and suggestions. As to what I'm trying to accomplish, I would answer improved handling, ride, fuel mileage and, hopefully, longevity. And, there's always the, "Cool" factor for being different. I know radials are better on cars, so I'm guessing the same would hold for bikes. My original thought was to use the same width (110 & 130) that are currently on the bike and drop from a /90 profile to a /80. I thought the stock rim width would then be OK.

    Now, to address other questions:

    My current ride is the fourth K75S I've owned. The first was a 1990 metallic blue that I purchased new. Number 2 was a 1992 Marakesh red and Number 3 was originally a 1987 metallic red that had been re-painted a really bright, clean white. Beautiful. I recently acquired #4 after #3 burned up in an accident. Current bike VIN ends in, "086". It is metallic red, original paint, has under 25,000 original miles and I got it from the estate of the deceased original owner. Needs some work due to neglect and not being ridden, but I'm pleased with it.

    Again, thanks to all for your help. I'll let you know which direction I end up going.
    Alan

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    K100RS 85 w 156k miles: Bought bike used w 37k and wider rear wheel already on it.

    With wide wheel and modified center stand I've always used Michelin Pilot Road RADIALS front and back, several different slight name changes since ''94. I'm very happy with them. When I change rear, I back center stand onto 2x8 board that lifts rear fender 1.5", then wheel rolls out with low pressure, when I "roll" it back in I make sure not to push bike forward off center stand because wheel with all new tread goes in tight.

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    Quote Originally Posted by am48@mail.com View Post
    Current bike VIN ends in, "086". It is metallic red, original paint, has under 25,000 original miles and I got it from the estate of the deceased original owner. Needs some work due to neglect and not being ridden, but I'm pleased with it.


    Alan
    150086 was five bikes behind mine on the assembly line May 16, 1986. That was the second day of US spec S production. They built 53 of them the day before.

    Congratulations, you have one of the "Original Litter"!

    http://www.bmwmoa.org/forum/showthre...riginal+litter


    Last edited by 98lee; 12-03-2013 at 06:27 PM.
    LONG MAY YOUR BRICK FLY!

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    Lee Fulton Forum Moderator
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  11. #11
    am48@mail.com
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    Quote Originally Posted by 98lee View Post
    150086 was five bikes behind mine on the assembly line May 16, 1986. That was the second day of US spec S production. They built 54 of them the day before.

    Congratulations, you have one of the "Original Litter"!

    http://www.bmwmoa.org/forum/showthre...riginal+litter


    That's awesome! And, good to know. I feel doubly-blessed, as #3's last three were, "156". So, that's TWO, "Original Litter" S's I've owned. Amazing. Thanks for the info.

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    Quote Originally Posted by am48@mail.com View Post
    That's awesome! And, good to know. I feel doubly-blessed, as #3's last three were, "156". So, that's TWO, "Original Litter" S's I've owned. Amazing. Thanks for the info.
    150156 built 5/23/1986. The third day of US spec production. They built 120 bikes 5/15-16/1986. I guess they might have switched to non-US spec bikes for the interveneing week.


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  13. #13
    Benchwrenching PGlaves's Avatar
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  14. #14
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    Quote Originally Posted by PGlaves View Post
    019
    5/15/1986 (probably mid morning, as only 53 were built that first day)

    Red Metallic 575







    Last edited by 98lee; 12-03-2013 at 06:35 PM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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