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Have I made a total c*ck-up?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by benjie, Dec 5, 2013.

  1. benjie
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    benjie Member

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    Had a rather spectacular tyre blow-out today. Not fun on the M4 at 6.30am. Ive already ordered a pair of new tyres, due for fitting Friday. I've just checked & noticed I've ordered the wrong size. On the back I have 235/40/18 and on the front I will have 235/45/18 - a 5% difference in the aspect ratio. Will this have a negative effect on the car…it's quattro & I don't want to ruin the diff.
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  2. DieselJake
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    DieselJake God Mode

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    It'll knock the speedo out a bit but it's not the end of the world, ask to change for the same set of tyres though if you can.
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  3. desertstorm
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    desertstorm Member

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    From what I have read certainly not adviseable to run different size tyres front an rear on a proper quattro car with a torsen diff.
    Tyre Size Calculator - Legal Requirements - Etyres says there is 3.7% difference in the diameter which translates to the 235/45 tyre being 24 mm bigger in diameter than the 235/40 . So the car will have 12mm more goround clearance at the front and it will be quite noticeable i would have thought.
    The manual says all wheels should have tyres of the same make, tread pattern and size, I think thats taking it a little far.
    Other posts I have seem where people are unning staggered set ups seem to indicate a 3% difference at maximum is OK.
    As you are outside of event that and there is a noticeable difference in the size I would say don't fit them.

    Karl.
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  4. Mike.M
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    Mike.M Active Member

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    I would try and cancel/exchange the order with the 40 profile myself
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  5. benjie
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    benjie Member

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    Thanks for the input guys, just wanted to check. I'm going to replace all of them - better to be safe than sorry. I was planning on it after Christmas anyway.
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