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Wheel Guide

Discussion in 'Modifications and Styling' started by suj, Jul 3, 2010.

  1. suj

    suj Wheel Connoisseur

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    alot of people get confused by wheels, due to ET's, PCD's etc
    so i thought i will try and explain them easily for you :)

    PCD
    this is the "Pitch Circular Diameter"

    basically this is the number of holes, by the diameter

    so if you have 4x100 wheels for example, then the 4 signifies the number of holes (in this case 4)
    the 100 is the diameter (distance from one centre of the hole to another)
    the way i think of it is, from the centre of the bolt hole to the centre of hub (this is radius) multiplied by 2 (which equals diameter)

    [​IMG]

    this picture shows the PCD

    Overcoming Close PCD Wheels
    Close Size Wheels
    sometimes, if you get PCD's that are close to yours, you can use "wobble bolts" to help movements of 0.5-1.25mm per bolt, so 1.0-2.5mm overall
    they sound dangerous, but they are not at all, they have special washers that when torqued up do not move about when driving, but they allow you to put close sized PCD wheels on

    for example, mini wheels are 4x101.6 (or 4x4") as you can see there is a 1.6mm difference
    so using wobble bolts, these wheels can be fitted to a 4x100 care

    Adapters
    sometimes the PCD's are totally off, like porsche wheels have 5x130 PCD, but my car has 4x100

    so using adapters (like spacers) you bolt the adapter to the hub with allen key head bolts
    then this then has a hubcentric centre, where you put the porsche wheel onto it, then bolt upto like usual

    with the use of adapters, you can get desirable wheels you could not put on before onto cars they wouldn't normally fit, but there are always cases where you cannot put them on (is explained later on)

    --------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Centrebore
    each make of car has different centrebores, which also need to be calculated, as this keeps the wheel "hubcentric" to the centre, so you don't get rotational vibrations

    on the last pic it shows the centrebore too

    Ways To Overcome different sizes
    if you purchase new wheels, you can do 2 things depending on the size
    centrebore = too small?..... then you can get this increased from an engineering firm
    centrebore = too big?....well you can get "spiggot rings", these are plastic/metal rings that fit on the inside of the wheels to make the centrebore the correct size

    --------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Offset (ET)
    this is also very vital when buying new wheels for your car

    ET = the distance from the rear mounting face to the centreline of the wheel

    it can basically tell you how much your wheels will "poke out" or "tuck in"

    poke = literally that, how much it will poke out more that your wheels on at the moment (can cause rubbing on arches/illegal protuding wheels)
    tuck = how much it will go inwards more than normal wheels (causing possible scraping of the suspension struts)

    Maths For ET
    things needed to work it out:
    Width Of Wheel: from bead of wheel, to the other bead (as can be seen in the following pic)
    [​IMG]

    Backspacing Of Wheel: this is the distance from the rear lip to the rear mounting face of the wheel (which is also shown on the above pic)

    if the width of the wheel is in inches, then multiply it by 25.4 to get total width

    so here is an example of how to work it out
    I have a wheel that is 8" wide, and has a backspacing of 153.9mm

    ET = "Backspacing" - "Centreline"

    centreline = "wheel width" / 2 (divided by 2)
    centreline = 8 / 2 = 4"
    centreline = 4 x 25.4 = 101.6mm

    ET = backspacing - centreline
    ET = 153.9 - 101.6 = +52.3


    *the positive sign, signifies the rear mounting face is closer to the outside of the wheel, meaning it will tuck more
    a negative sign, signifies that the rear mounting face is closer to the inside of the wheel, meaning it will poke more

    Helpful Site To Work Out Differences
    http://www.1010tires.com/WheelOffsetCalculator.asp

    typing in your old offset of wheels/width, then the same for the new, it will tell you how much poke/tuck you get on the wheels

    --------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Common Problems

    1) What happens to the offset if i get wheels that require adapters?
    A) well if you use adapters, the backspacing is the distance from the rear lip to the rear mounting face (where you would add on the adapter)
    but the easier way would be to calculate the ET, and then just take away the width of the adapter

    so for example if you have a wheel with ET52.3, and use a 20mm adapter, then the new offset will be ET52.3 - 20 = ET32.3

    2) what width/ET wheels can i get away with without doing too much arch work?
    A) your best to use the site i posted above, and compare to the wheels you have, it will tell you how much extra poke/tuck you will achieve, so you can then get the measuring tape out, and see where the wheel will come upto on the car

    also the tyre you put on will also determine the scrubbing, that is why alot of people put slight stretch on tyres to overcome this
    (stretch is putting a slightly smaller tyre, so the tyre wall becomes angled, eliminating/reducing scrubbing

    3) are there any PCDs that cannot be put together by using adapters?
    A) yes there are, there are a few that cause overlapping of bolt holes, so some companies will not make them, some have made a few ways to overcome them, but people think they are not safe, but that is always down to your own preference (I will not be held responsible if you buy them and they do fail, as I have ran them with no problems, but all cars are different)

    4) how would i work out the ET of split rims, if the inside barrel stays the same, and i add wider lips?
    A) this can be a little trickier, there is 2 methods to do this, you would work out the backspacing (as this will not change) then take away half the new width

    so on some BBS RM's they are ET33, with a 6.5" width (0.5" lip), so backspacing = ET + centreline (rearranging the equation)
    so backspacing = 33 + (6.5 / 2)
    backspacing = 33mm + 82.55 = 115.55mm

    then if you put on a 2" lip, this means the new width is 8" (as it had a 0.5" lip on it originally)
    so new ET = "backspacing" - "centreline"
    ET = 115.55 - 4"
    ET = 115.55 - 101.6 = 13.95
    ET14

    or you can do it another way i like is
    if using a BBS RM again, ET33 on a 6.5" wide wheel (0.5" lip)
    then using a new 2" lip
    it has a 1.5" wider lip
    so divide by 2 (as it moves the centreline by half)
    increase in centreline = 0.75" (19.05mm)

    new ET = old ET - "increase in centreline"
    ET = 33 - 19.05 = 13.95mm
    ET14

    --------------------------------------------------------------------------------------------------------------------------------------------------------------------

    hope this helps, if you got any problems, give me a shout, and i will try and help if i can :)

    Suraj
     
    #1 suj, Jul 3, 2010
    Last edited: May 17, 2011
  2. Art0ir

    Art0ir TDi Ho

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    Good guide, sticky imo!
     
  3. suj

    suj Wheel Connoisseur

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    thanks mate, i thought i'd make it, as i keep getting asked the same thing over and over, and thought it might help alot of people, as wheels are a bit confusing tbh

    i understand them quite well, which is why everyone calls me wheel-w.hore lol

    but if anyone does need help, drop me a PM, i will try and help where i can :)
     
  4. Brummy

    Brummy Nazi Moderator-Bot

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    Good thread, Suj... just playing with figures on my Cookies @ an ET of 23.. and just determining spacers of 15mm 20mm and 25mm to see how much they will poke etc.
     
  5. suj

    suj Wheel Connoisseur

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    no problem johnny boy, so ET8 and ET3? not too bad on a 7J tbh

    use that wheel offset calculator above to find out how much more poke/tuck you get compared to your borb a's :)
     
  6. phantombantam

    phantombantam NUFC forever!

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    Good thread. Can pcd adapters be bought in any width? Getting an Ibiza cupra soon and want to put on my Leon bbs seat sport wheels ( 18" )
    They are 5 x 112 with ET of 51. Ibiza is 5 x 100 but not sure of offset.

    PRATTY
     
  7. suj

    suj Wheel Connoisseur

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    Hi Pratty,
    sorry for late reply, did not check this

    yes they can be made in many sizes, 15mm is the smallest, but most people run 20mm's minimum (I have even seen people with 12mm ones, I wouldn't though lol)

    I am currenty running 5x100>5x112 adapters (with centrebore of 57.1 for both sides) to run Audi wheels on my VW Bora (25mm adapters)

    you need to find out the offset of your current wheels, the width of the new wheels too

    and how much more you want them to poke etc, drop me a PM when you have them all, will send you a reply with the offsets required (so then you can purchase the appropriate adapters)
     
  8. I dont know about wheel ***** after reading this useful info id call you a wheel guru im looking at some new style rs6 replicas for my leon cupra and tbh all the offsets etc was starting to get confusing lol many thanks for the useful post ;)
     
  9. jagzz88

    jagzz88 Active Member

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    This info is really helpful :) Cheers
     
  10. firstly apologies because i was going to pm you and then realised that I'm stupid and didn't know how.....

    stupidly i bought some second hand oz superleggera freshly "refurbished" which i was reassured would fit my seat ibiza fr tdi 2006 - needless to say they don't...

    The centre bore is way too small but the bolts seem to line up ok even though the holes are too small to get the wheel nuts through.

    help - what should i do - i have no idea what car they are from originally and I'm not sure if it would still be strong enough if an engineer were to machine them to fit.

    I don't even have the wheels is front of me but i do have some photos. I emailed oz to try and identify the fittament for the original car - they didn't even reply :(

    i bow down to you guys and your superior knowledge. They are 17" and look like they may have been gold originally.

    Its been such a flipping nightmare that I'm on the verge of putting the jeffing things in the bin!

    [:@]

    all help as always greatly appreciated :)
     
  11. suj

    suj Wheel Connoisseur

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    One option would be to do as you said:
    1)
    Machine the centrebore to the right size (I assume it's a MK2? so 5x112 PCD and 57.1mm centrebore?) then get bolt holes widened out (are MK2 Leon's M14x1.5 bolts? someone to confirm please?)

    2) get some custom adapters, they would have to be 20mm minimum, so you need to make sure the wheels will fit?
    So you will have the adapter to bolt onto the hub, then the wheel would bolt the adapter to the right PCD and centrebore.


    You sure the wheel hasn't got a spigot ring on (this is a ring put into the wheel, can be plastic or metal that corrects it for the right car).
    Check the inside of the wheel and try pulling anything out.

    You cannot PM as you need minimum of 15 posts and when you do get there need verifying by a mod.

    When you do get there post up some pics of wheels (rear as well).
     
  12. Hi,

    Its an Ibiza fr 130 tdi 2006 - the wheels now ive got them back seem to have no spigot rings - they were previously gold as well ive realised - leading me to think they were probably off a scooby imprezza? is that possible - now i have them back - i can take photos etc and can take any measurement help you guys help me :)
     
  13. ive measured the centre bore with a tape measure (i have no vernier calipers :( ) the actual hole iteself is maximum 55mm id say whereas the scooby should be 56.1? Also the bolt holes are just too small - im so confused that it physically hurts... :blink:
     
  14. suj

    suj Wheel Connoisseur

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    If the centrebore is too small, needs boring out to 57.1, and bolt holes will be m12 for a scooby, so will also need opening up to let M14 go on.
     
  15. seatleon2012

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    hello there currently running calibre askari wheels 7x17 et35 but wanting to go 8x18 et 35.... the rears are 9.5x18 just wanted to know how much gap would leave me between tyre/wheel and rear suspension without cathing or rubbing im also running 20mm spacers.. or would i be best with 8j wheels all round
     
  16. golfguy

    golfguy Active Member

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    Very useful information ta.
     
  17. rumple

    rumple Guest

    Very useful, thank you
     
  18. Shrako

    Shrako Active Member

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    Good read, thank you

    Sent from my Nexus 4 using Tapatalk
     
  19. Bikerboysmiler

    Bikerboysmiler Active Member

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    Hello folks. Can anybody advise whether I can run golf 15inch mk5 1K0 601 025A wheels on my 2.0 Tdi Altea Sport please? I want to run winter tyres in this size. Got a lead on the perfect set except they are 15" not 16"...
    Thanks


    Tyler
     
  20. Bikerboysmiler

    Bikerboysmiler Active Member

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    Never mind, they fit...


    Sent from my iPad using Tapatalk
     

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