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  1. #1
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    Default 5 x 4.5" Wheels and Adapters to HQ

    Hi friends,

    I am not much familiar with the subject and I hope I will get some expert advice here.

    Mine is a 74 Holden HQ sedan. I have read its wheels have 5 x 4.75" PCD.

    I have a set of genuine 15" x 7" Magnum 500 rims, but they have a PCD of 5 x 4.5". (I know Mustang wheels but hey, I got an entire set for like 100 bucks and looks a lot similar to GTS rims)

    To fit these to the HQ, I have to use adapters.

    However, these rims have a back spacing of 4.25" and an offset of 6mm according to the specification.

    What I would like to know is, the ideal thickness of the adapter so that it stays within safe tolerances.

    Interested to see the calculations as well.

    Thank you




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  2. #2
    Not the Kingswood! hq308's Avatar
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    I have 15 x 7 with a 4" backspace on the front of mine and with a 225/60/15 it will catch on the guard at full steering lock on uneven ground. Mine is reasonably low though. That gives you 1/4" difference to what you have (4.25" backspace). With a narrower tyre and hopefully not as low as mine you might get away with 1/2". My worry is if you can even get an adapter that narrow.

    On the rear I have 15 x 8 with 4.5" backspace and 235/60/15 (standard wheel arches) and they just fit. A 15 x 7 4" BS would sit in the same place in the wheel well so again your 4.25 BS gives you 1/4" to play with. You could gain a little more by rolling the lip on the wheel arch and/or a narrower tyre.

  3. #3
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    hi
    1/ Swapping stud patterns is not done unless the rims can be professionally re-drilled . Preferred way vs least desirable of using adapter plates .
    2/ If Centre bore is small will require machining larger ?? OR Then the locating centre bore adapter will be required if centre bore to big.
    [ most rims have provision for this ]
    Last edited by swampy; 17-05-2022 at 12:32 PM.

  4. #4
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    Quote Originally Posted by hq308 View Post
    I have 15 x 7 with a 4" backspace on the front of mine and with a 225/60/15 it will catch on the guard at full steering lock on uneven ground. Mine is reasonably low though. That gives you 1/4" difference to what you have (4.25" backspace). With a narrower tyre and hopefully not as low as mine you might get away with 1/2". My worry is if you can even get an adapter that narrow.

    On the rear I have 15 x 8 with 4.5" backspace and 235/60/15 (standard wheel arches) and they just fit. A 15 x 7 4" BS would sit in the same place in the wheel well so again your 4.25 BS gives you 1/4" to play with. You could gain a little more by rolling the lip on the wheel arch and/or a narrower tyre.
    I checked out and found the adapters are 1 inch thick. Found on https://www.ebay.co.uk/itm/272489437...mis&media=COPYeBay.

    I think I can get one tyre shop I know, to help me out fitting tyres that wouldn't rub on the body.

    My biggest concern is, having 1 inch thick plate to the hub, would that have any detrimental effect on the wheel bearings or vehicle dynamics?

    If so, how bad it would be? Are there any tolerances recommended by these pro modding guys?

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    Last edited by Thutmose HQ_74; 18-05-2022 at 05:09 AM.

  5. #5
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    Quote Originally Posted by swampy View Post
    hi
    1/ Swapping stud patterns is not done unless the rims can be professionally re-drilled . Preferred way vs least desirable of using adapter plates .
    2/ If Centre bore is small will require machining larger ?? OR Then the locating centre bore adapter will be required if centre bore to big.
    [ most rims have provision for this ]
    These are the rims. Did you mean there should be another set of 5 holes drilled to the rim at 4.75" to match the hub?

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    Last edited by Thutmose HQ_74; 18-05-2022 at 05:13 AM.

  6. #6
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    Seem to be going to alot of trouble for a set of $100 rims. If you have a 1 inch adapter your wheels will stick out a mile. also load up the bearings, Keep the car safe and fit the right rims .

  7. #7
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by Thutmose HQ_74 View Post
    I checked out and found the adapters are 1 inch thick. Found on https://www.ebay.co.uk/itm/272489437...mis&media=COPYeBay.

    I think I can get one tyre shop I know, to help me out fitting tyres that wouldn't rub on the body.

    My biggest concern is, having 1 inch thick plate to the hub, would that have any detrimental effect on the wheel bearings or vehicle dynamics?

    If so, how bad it would be? Are there any tolerances recommended by these pro modding guys?

    Sent from my SM-J730F using Tapatalk
    Moving the wheel out further away from the hub will place extra load on the wheel bearings so not ideal.

    If you really want to use those wheels I feel you have 2 options.

    1) have the offset of the wheels changed. The centre of the wheel is welded to the outer, a good engineer could carefully machine the welds and move the centre to a more suitable position and re-weld it to the outer. They would increase the backspace to account for the 1" adapter.

    2) Have your hubs/axles re-drilled to 4.5" stud pattern.

    Option 1 is probably the easiest to do, both options involve finding a specialist or a good engineer.

  8. #8
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    Quote Originally Posted by hq308 View Post
    Moving the wheel out further away from the hub will place extra load on the wheel bearings so not ideal.

    If you really want to use those wheels I feel you have 2 options.

    1) have the offset of the wheels changed. The centre of the wheel is welded to the outer, a good engineer could carefully machine the welds and move the centre to a more suitable position and re-weld it to the outer. They would increase the backspace to account for the 1" adapter.

    2) Have your hubs/axles re-drilled to 4.5" stud pattern.

    Option 1 is probably the easiest to do, both options involve finding a specialist or a good engineer.
    Got it, thank you

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