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WHEEL AND TYRE SIZE EXPLAINED (also list of tried and tested wheel/tyre combos)

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by DALE_AVANT, May 12, 2012.

  1. DALE_AVANT

    DALE_AVANT Avantage
    Audi Avant Owner Group Audi A4

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    TYRE WIDTH:

    Also called 'section width'. This is the width of the tyre in millimetres (mm). So if a tyre is 235/40/18, the tyre is 235mm wide (9.25 inches/23.5cm).



    TYRE SIDEWALL:

    Also called 'sidewall aspect ratio'. This is the measurement of the side wall of the tyre. It is not a cm/inches measurement, but a percentage of the tyre width.
    For example, a tyre size for a 195/50/15 tyre could be read as '195mm wide/50% of 195mm = 97mm sidewall height/15inches wheel size'. So the sidewall height is actually 97mm (3.8inches/9.7cm).



    TYRE SIZE (WHEEL SIZE):

    This is the size of wheel the tyre should fit onto. For example, a tyre size of 235/40/18 should be suited to an 18inch wheel.



    WHEEL SIZE (DIAMETER):

    This is the usual term for describing wheel sizes. An 18 inch wheel has a diameter of 18inches.



    WHEEL WIDTH:

    When looking to fit new wheels you need to know how wide they are. This is usually stamped on the rear of the alloy, followed by a letter. Usually, it is something like '8J', where the '8' means '8inches wide'.



    STUD PATTERN:

    Also called the 'PCD' (pitch circle diameter). This is the number of wheel bolts per wheel and the pattern they form on your wheel and hub.
    For example, your average Audi A4 has a PCD of 5x112. This means 5 bolts per wheel, set out in a circle measuring 112mm.



    OFFSET:

    This is the distance in millimetres from the wheel hub on the car to the centre of the wheel.
    In simple terms, a wheel with an offset of '35' will stick out more from the arches than one with an offset of '55' (assuming all other wheel measurements are the same/wheel width etc). Some people use 'spacers' that sit between the wheel and the hub to make their wheels stick out more. Adding a 10mm spacer would reduce the offset by 10mm.




    **PLEASE ADD YOUR 'TRIED AND TESTED' WHEEL AND TYRE COMBINATIONS BELOW TO GIVE OTHERS AN IDEA OF WHAT WILL AND WON'T FIT. ALSO ADD YOUR VEHICLE MODEL AND ANY RELEVANT MODIFICATIONS (LOWERING SPRINGS ETC)**




    Also, links below (thanks to myturbodiesel.com) for OEM Audi wheel sizes for 5x100 and 5x112 wheels:

    16" and 17" Audi stock wheel gallery database5x100
    18" VW and Audi wheel picture gallery and database 5x100 bolt pattern

    15" and 16" audi OEM wheel pics 5x112 bolt pattern
    17" Audi 5x112 wheel gallery
    18" Audi 5x112 wheels
    19 20" 21" VW and Audi wheels 5x112
     
    #1 DALE_AVANT, May 12, 2012
    Last edited: May 12, 2012
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  3. DALE_AVANT

    DALE_AVANT Avantage
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    B6 Audi A4 Avant 1.9 TDI Sport.

    TYRE SIZE: 235/45/17.
    WHEEL SIZE (DIAMETER): 17".
    WHEEL WIDTH: 7.5J.
    STUD PATTERN: 5x112.
    OFFSET: ET45.

    [​IMG]
     
    #2 DALE_AVANT, May 12, 2012
    Last edited: May 12, 2012
  4. archemist

    archemist Member
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    there's many a tyre size calculator out there but here's one:

    TRC Calculator

    as you posted (in the other thread) it's the Rolling radius that's important (douby so with a quattro / permanent 4wd)

    also that 235 in a michelin isn't necessarily 235 in a Goodyear. The amount of rim protection and side wall shape profile can all be signiificant. I had a Volvo V70 on 18" BBS split rims (i didn't pay the £1800 option price mind) and they were fine on vredsteins but not goodyears due to front wheel scrub on brake line / inner wheel arch.

    I run Michelin Pilot sport2's on S4 Avus 18s et 45 8 inch rims and 235/40/18's and they're normal load (as far as i can determine even a behemothic barge like mine still runs on normal load tyres). Not surprisingly they run without issue with the std 20mm lower sport chassis.

    PCD is a little confusing as it's the circle drawn from the centre of the wheel through the centre of the wheel bolts (hence USA use Bolt circle diameter (BCD))

    and not forgetting that a tyre could have 9mm of tread or 2mm of tread (+/7mm on radius and 14mm diameter or twice pies x o/a radius rollling)
    cheers And
     
    #3 archemist, May 12, 2012
    Last edited: May 13, 2012
  5. archemist

    archemist Member
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  6. archemist

    archemist Member
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    Replying to my own thread - quattro's are marginal for 91y tyres - early s4's had them and the axle loading is right on the limit - "some owners with some tyres" had problems which might be explained by the relatively soft sidewalls.

    Audi, changed to min 94 tyres and it's my thinking that any B6 (apart from the 1.6) should probably have 94 load tyres on the front.

    There's a thread somewhere with the links when I can find it!
     
  7. Az

    Az Hard slammed!

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    I've been running these on my B6 Quattro for a couple of years:-

    19"x9.5" on all 4 corners <----------- For sale, cheap plug! :p
    ET38 all round
    Spigot rings fitted (no issues)
    235/35/19 tyres all round
    KW coilovers lowering the car approx 50mm

    No spacers, no arch work, no rubbing.

    Also taken delivery of my new wheels today, not far off of the spec of my old wheels above,....

    19"x9.5" on all 4 corners again
    ET45 all round
    235/35/19 tyres
    Obviously on the same coilovers lowered the same amount.

    This time I'm running 5mm spacers all round to give a final ET40

    As above, no arch work or rubbing.


    EDIT....... Wasn't happy with the finish of the new wheels so sent them back, ordered the same wheels as I currently have instead (OCD getting the better of me)
     
    #6 Az, May 23, 2013
    Last edited: May 23, 2013
  8. DALE_AVANT

    DALE_AVANT Avantage
    Audi Avant Owner Group Audi A4

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    [​IMG] TYRE SIZE: 235/40/18.
    WHEEL SIZE (DIAMETER): 18".
    WHEEL WIDTH: 8J.
    STUD PATTERN: 5x112.
    OFFSET: ET43.
     
  9. krisavant

    krisavant 4th set of a wheels in a year

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    A3 version
    [​IMG]

    Tyre size: 235/40/18
    Rim size: 18"
    Width: 8J
    Stud pattern: 5x112
    ET: 54. Needs spacers or will rub on front on full lock, at least 15mm or more to look right.
     
    #8 krisavant, May 23, 2013
    Last edited: May 23, 2013
  10. krisavant

    krisavant 4th set of a wheels in a year

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    [​IMG]

    A5 alloys
    245/40/18
    5x112
    ET 29
    8.5j
    66.6 centre bore (spigot rings sort that)

    Tyre could do with 235's to stop arch rubbing when going over bumps.
     
  11. gruf

    gruf Member

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    You have forgot LOAD INDEX.
    This seems to be looked over quite a lot.
    Especially if your like me and think the bushes need changing every 5 mins Coz you feel to much of the road surface and I mean TOO MUCH.

    This is to compensate for extra weight or loss of weight.
    If you don't get these right the ride will either feel to bumpy or to much sway.
    I've noticed when I had 95y it felt good that's what was on when I bought my car then when I got new 91y the car seemed to glide more instead of feeling all them hair line cracks and ants on the road with the 95y's on. So the bushes weren't faulty or fake it was the boots that were the trouble.
     
  12. Gazwould

    Gazwould Well-Known Member

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    [​IMG]

    Tyre calculators are just a rough guide because tyre manufacturers don't produce them to exact size .
     
    DrStrange likes this.

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