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Thread: Rolling radius

  1. #1
    2nd Gear

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    Rolling radius

    I am considering fitting a new set of new wheels to my rs4. The fronts are 8" wide the rears 9" wide. Will i have issues if i run 215/35/19 on the front and rear? I am happy to run a stretch on the rears in an attempt to keep the rolling radius the same.

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  3. #2
    "Stick a V8 in it!"

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    215's are surely far too narrow?

    Especially on an RS, they run 255's as standard?

    running the same tyres front and rear is fine, but 215's is just going to look silly on a RS.

    245/30r19 or 255/30r19 might be a shout?

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
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  4. #3
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    I think they will be to narrow, but i was using that size as an example as those are the size of the tyres currently fitted to the wheels.

    I think that might be a good shout, so there doesnt have to be to big a size difference to keep the rolling radius in check?

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    "Stick a V8 in it!"

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    the rim width doesnt effect the radius a huge amount, so as long as the tyres are the same size front and rear i recon it'll be fine.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


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    when going up or down in wheel size.... its the profile/aspect ratio that you change to keep the rolling radius the same or similar. not so much the width, but it can be juggled around within reason to get near the original rolling radius.

    205 55 r16

    the 55 is a percentage of the width. 55% of 205.

    always go a little under the original rolling radius rather than over. nothing wrong with your speedo under reading, but over reading can be a problem for obvious reasons.

  7. #6
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    Is there something like a calculator that can work this out? It would make getting the correct tyre size easier

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    "Stick a V8 in it!"

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    Googling "tyre calculator" finds a few options.

    I've used this one before:

    Tire size calculator

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  9. #8
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    Quote Originally Posted by aragorn View Post
    Googling "tyre calculator" finds a few options.

    I've used this one before:

    Tire size calculator
    Thanks, I will give that a try.

 

 

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