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Is 225/40/18 front and 235/40/18 back OK?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by pengjn, Jul 25, 2010.

  1. pengjn
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    pengjn Member

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    [Jul 25, 2010]
    I bought a set of OEM RS6 alloys from ebay, had them refurbed and they are now mint. Only snag is that they are 225/40/18 on the front and 235/40/18 on the back. Before I jump in and buy the rubber, can anyone tell me if they are going to fit my car properly and if I'm going to have any issues with them?

    PS I'm planning on fitting Eibach springs to lower it to the same height as an S-Line, so not sure if this will make any odds?
    :think:
    Last edited: Jul 25, 2010
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  3. akash_sky1
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    akash_sky1 Active Member

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    [Jul 25, 2010]
    Since your is a 2wd it won't matter if the rolling radius is slightly bigger at the back then the front, but the rear tyres may rub I think if you slam it, a 30 mm would be ok though I would have though.
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  4. sub39h
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    sub39h Active Member

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    [Jul 25, 2010]
    are you sure they had the right rubber on 'em? if they're OEM A3 RS6s shouldn't they be 225/40 R18 all around?
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  5. ghouseman
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    ghouseman Gazza

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    [Jul 25, 2010]
    thought rs6 had 19s
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  6. AudiS3-Turbo
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    AudiS3-Turbo Member

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    [Jul 25, 2010]
    they are both 40 profile and this will have no affect between the rolling radius of the tyres.
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  7. dinsdale66
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    dinsdale66 New Member

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    [Jul 26, 2010]
    Not true. the "40" is a ratio of the tyre width to sidewall height. 235/40R18 is a bigger diameter and circumference than 225/40R18.

    http://www.exploroz.com/Vehicle/Tyres/SizeCalc.aspx
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  8. pengjn
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    pengjn Member

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    [Jul 26, 2010]
    Bit confused now but that is partly due to big night out last night. I thought the 225-235 bit was just the width?
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  9. lincoln_dj
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    lincoln_dj Member VCDS Map User

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    [Jul 26, 2010]
    it is, the width in mm. but the 40 part means the "thickness" of the tyre is 40% of 225mm (ie 90mm, or 94mm if 235mm wide)

    would assume this could cause wheel speed sensor fault? certainly on 4wd cars...
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  10. akash_sky1
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    akash_sky1 Active Member

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    [Jul 26, 2010]
    His car's 2wd and hes running the larger rolling radius on the back so it shouldnt cause problems with that.
    #9
  11. v1raj
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    v1raj Member

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    [Jul 26, 2010]
    I'm currently running this profile tyre setup on a set of Rossos.

    No problems at all mate, go for it :o.k:
    #10
  12. pengjn
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    pengjn Member

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    [Jul 26, 2010]
    Thanks v much everyone - good to know I have screwed up totally. Can't wait to get the new wheels on there - I've lived for far too long with the 17" Stars.
    #11
  13. AudiS3-Turbo
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    AudiS3-Turbo Member

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    [Jul 26, 2010]
    I learn something new everyday! thats also a usefull link thanks.
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