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wheel/tyre size changes- speedo incorrect??

Discussion in 'Handling' started by trekbiker, Oct 9, 2005.

  1. trekbiker

    trekbiker Member

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    I'm currently running 265/30/19 on a B6 avant , which i have been told by an experienced employee of ATS are 10mm bigger in overall circumference than the standard fit of 205/55/16 or 235/45/17 which would normally be standard fit.

    these wheels were fitted by an Audi dealer from new. I have 2 questions:-

    1. Would the speedo read slower than i'm actually going and by how much(is there a calculation?). would the mileage also be affected as my MPG, which i have worked out by brimming the tank against the mileage(supposedly) done?

    2. Would a smaller tyre, say a 235/35/19 be better? /ubbthreads/images/graemlins/noidea.gif

    Any help please!
     
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  3. sash

    sash Member

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    if you want the speedo to remain accurate you need to keep the rolling circumference pretty much the same.

    You can use this calculator to determine best tyre size:

    http://www.miata.net/garage/tirecalc.html
     
  4. trekbiker

    trekbiker Member

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    thats really handy, top link thanks /ubbthreads/images/graemlins/beerchug.gif
     
  5. jojo

    jojo Looking for Boost!
    Staff Member Moderator Team Daytona quattro Audi S3 Audi A6 Audi Avant Owner Group

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    Silly question, do 265's fit on the front with no catching? and what brand tyres are they?
     
  6. trekbiker

    trekbiker Member

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    [ QUOTE ]
    Silly question, do 265's fit on the front with no catching? and what brand tyres are they?

    [/ QUOTE ]

    no catching, Audi put them on as new. I have conti sport contacts and 'Nexus'(??), think the former are on front axle
     
  7. jojo

    jojo Looking for Boost!
    Staff Member Moderator Team Daytona quattro Audi S3 Audi A6 Audi Avant Owner Group

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    [ QUOTE ]
    [ QUOTE ]
    Silly question, do 265's fit on the front with no catching? and what brand tyres are they?

    [/ QUOTE ]

    no catching, Audi put them on as new. I have conti sport contacts and 'Nexus'(??), think the former are on front axle

    [/ QUOTE ]

    Interesting, 265s seems overtyred for an A4, but if it doesn't catch.... why not huh
     
  8. trekbiker

    trekbiker Member

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    [ QUOTE ]
    [ QUOTE ]
    [ QUOTE ]
    Silly question, do 265's fit on the front with no catching? and what brand tyres are they?

    [/ QUOTE ]

    no catching, Audi put them on as new. I have conti sport contacts and 'Nexus'(??), think the former are on front axle

    [/ QUOTE ]

    Interesting, 265s seems overtyred for an A4, but if it doesn't catch.... why not huh

    [/ QUOTE ]

    cos of the cost per corner perhaps???
     
  9. rojocho

    rojocho Member

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    try tyresave.co.uk for tyre diameters really easy, just fill in the sizes it does the rest.

    also if you have a larger rolling diameter your speedo will read slow compared to your actual road speed, not good for speed camera's! /ubbthreads/images/graemlins/beerchug.gif
     

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