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3.2 SB owners - what tyre pressures are you using?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by jon208, Mar 21, 2011.

  1. jon208

    jon208 Member

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    There seems to be a bit of variety in the tyre pressures given for this car on the fuel flap sticker.

    My sticker gives several options for 17" wheels but for the 18" wheels the only option is 44psi all round (the pictures show that for a fully loaded car, with no option for a lighter load).

    Other 3.2 SB owners seem to have options for light loads on the 18" wheels of front 41 and rear 36. If nothing else this must give a less harsh ride.

    My car is 57 plate, any idea if Audi changed the PSI recommendation for 18" wheels on the SB?

    Could other 3.2 SB owners let me know what inflation pressures they've got for 18" wheels? If anyone knows of a reason for the change then that'd be interesting to hear too.

    Thanks
    Jon
     
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  3. col6821

    col6821 Member

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  4. paddy

    paddy Audi=No fault code, no idea

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    jon
    I think if you dig deep the reality is it varies between tire manufacturers. I think if you have limited info for your tires i would start at about 38 all-round and watch carefully for wear. If the centre of the tread looks to be wearing drop the pressure, if the inside edges look to be taking the wear raise the pressure a bit..What i wouldn't do is run under 35psi because you will use petrol and the steering will be heavy.
     
  5. jon208

    jon208 Member

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    Thanks Paddy, the car currently has Michelin Exaltos all round. They've got about 3mm left so it won't be too long until it's time for a new set. I think I'll back off from the 44 all round as the car is usually lightly loaded and it's made the ride noticeably harsher. Maybe front 41 and rear 36 might be a starting point?

    The only thing I was worried about was whether Audi has raised the recommended PSI for 18" wheels to reduce the chance of rim damage on cars with the bigger wheels/lower profile tires - which may explain why my '57 plate 3.2 SB has a different fuel flap sticker to other 3.2 SBs.

    Jon
     
  6. paddy

    paddy Audi=No fault code, no idea

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    Bigger tires would want more pressure anyway and all S-line SB's would have had 18" wheels regardless of year. My 3 door is 04 and that has 18" as std.
     
  7. LWNY

    LWNY Member

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    Audi can't up the pressure recommendations just so that there will be less chance of rim damage. Doing that would just cause undesired handling characteristics and shorten the life of the tire.

    There should be a calculator out there that takes into account the max pressure/load of a tire and scale that pressure relative to the weight put on the axle by the car, taking into account of the atmospheric pressure (I see some calculations that doesn't take that into account, thus arriving at some ridiculous low tire pressure). But it also has to factor in tires that has super stiff belts that deform less with more air (which is not possible), thus throwing the linear relationship between pressure/load into the trash. I think there are max load for given PSI tables for individual tires out there, but that is not public information. If we have that, then we are all set.

    Anyway, the optimal tire pressure is one where there is even pressure applied across the width of the contact patch. The easiest way to is to draw a thick chalk line across the whole width of each tire, drive the car some short distance, then check for the chalk mark wear.
     

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