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Thread: Wheel Widths J's & K's?

  1. #1

    Wheel Widths J's & K's?

    Hi Guy's,

    Wondering if anyone can answer a question about wheel measurements. I've got some steel wheels which are 4.5J and 5.5J, I've seen some of the early 904 & 906 front wheels with a measurement of 5K. Obviously the numbers don't pose a problem , but what's the difference between a J measurement and a K measurement?

    Cheers
    David

  2. #2
    Senior Member
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    David - The J, K, etc signifies the physical shape of the wheel where the tyre bead meets it - represented by the portion arrowed in the following diagram.

    Different combinations of the height/width/radius account for the letters used (J, K, etc)
    Attached Images Attached Images  
    Andy

    Early 911S Reg #753
    R Gruppe #105

  3. #3

    Following diagram?

    Hi Andy,

    Thanks for the info, do you have a picture?

    Also, I remeber you offered me a copy of the SWB sport usage manual, would that still be OK? I'm after the suspension section really.

    Thanks
    David

  4. #4
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    David - I don't know what happened to the diagram - it was there in my original post this morning !

    Anyway, here it is again:

    As for the Sports Purposes Manual, email me your address & I'll copy/post it on Monday (email: andyjboy@hotmail.com)
    Attached Images Attached Images  
    Andy

    Early 911S Reg #753
    R Gruppe #105

  5. #5
    Ah ha, it's appeared now, thanks. I never realised rim designs were this complicated, I've never seen a diagram like that before. So would the differences be due to a J wheel using road tires and the 904/906 K wheels using racing tires? I'm trying to understand why these would be different?

    I'll drop you an email Andy, I realy appreciate you making the copy for me. Are you going to Ragley on Sunday?

    Cheers
    David

  6. #6
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    I had a set of 904 wheels last year so I'll post the comparison of profile vs a std (albeit 6J) 911 steel wheel:



    Andy

    Early 911S Reg #753
    R Gruppe #105

  7. #7
    Senior Member
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    It's difficult to see much of a difference in the photos (if you ignore the safety bead) but I would say the 904 edge profile (lhs) looks slightly more 'compressed' - ie the height:width ratio of the area arrowed in the first diagram seems higher.
    Andy

    Early 911S Reg #753
    R Gruppe #105

  8. #8
    I remember seeing your set on eBay and kick myself daily for not buying them!

    I don't suppose you know what they weighed do you Andy?

    I've sent you my address BTW

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