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Front/Back size staggering

Discussion in 'Z3 Roadster & Coupé' started by r37, Jan 29, 2012.

  1. r37

    r37 Dedicated Member

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    Since my stock rims have failed me im in the market for some aftermarket ones which got me thinking. Staggering the width from the front to the back makes perfect sense, but why not stagger the size of the wheel aswell. Having a 17 on the front would preserve things like the speedo, cornering and breaking and then 18's on the back to fill the arches and because they usually are available in wider widths. I know there are several supercars that use this setup but im not sure if it would unbalance the zed which wasnt designed for it and its a rather expensive lesson to learn. I cant see any downsides to it other than trying to buy such an unusual set of wheels and i think it might give the zed a more aggresive stance on the road but if it unbalances the car than its pointless. Anyone have any thaughts?
     
  2. billz

    billz Zorg Expert (I)
    Supporter British Zeds

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    If you have the correct size tyres and set up on 18s then the speedo reads what it would with the stock 17s. We are running 9" with 255/35 rear and 81/2 with 225/40 fronts. Checked against the satnav the speed is the same as when we had the 17s on.
    bill
     
  3. Aceman

    Aceman Moderator
    British Zeds 3rd Party Trader

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    Also the speedo pickup is located in the diff so measures from the back wheels !

    The only thing I would say about going for a larger diameter wheel is that the bigger you go the more weight of the wheel is on the outer circumference and this translates into higher inertia hence can be felt in slightly reduced acceleration. I came across this a few years ago when I had an Ibiza TDI and went from 16" to 17", with the 16's on it noticeably felt sharper off the mark than with the 17's on. Oh and the harsher ride due to smaller sidewalls was quite noticeable too.
     
  4. stevie_a

    stevie_a Zorg Guru (IV)
    Scottish Zeds

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    Try this HERE for tyre size.. :-bd
     
  5. hard top

    hard top Zorg Expert (I)
    Dutch Zeds The M44 Massive

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    I now that this is not really a comparison but I had this on a Merc and thought it looked really B-)
     
  6. r37

    r37 Dedicated Member

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    a 17x40 and 18x35 have a rolling diameter within 1mm extra or 0.16% which is pretty much the same. So a hypothetical setup of 17x45x8.5j on the front and 18x35x9.5j on the back would give the same circumference all round and should leave the speedo/gearing the same as stock plus having a 17 up front means that the 8.5 width would fit with room to spare where the 18 wouldnt. Only thing im thinking now is the traction controll. Even though the circumference is within 1mm which is nothing would the traction controll still kick in because of different readings from the front and back or is 1mm within its tolerances?
     
  7. Devon Z

    Devon Z Zorg Legend
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    Have you a style of wheel in mind as matching may be a problem, but an interesting idea :-?