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Thread: Wider tyres and fuel economy.

  1. #1
    Grandmaster jacqvt's Avatar
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    Default Wider tyres and fuel economy.

    My Jetta 4 TDI has 16 inch tyres, the tyre size currently is 205/55/16, so the tyres is 205 wide. I know of someone who fitted 225 tyres on a Audi with the same size wheels as my Jetta.

    So I've been thinking of doing the same when I must replace mine. What do you think, will the 20 mm wider tyre interfere with the fuel economy?

  2. #2
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    It surely would. Dont know to what noticeable extent though.
    "We live in a monetary paradigm that demands infinite growth, so balance is not possible." Michael C. Ruppert

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    Super Grandmaster Fazda's Avatar
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    There is possibly a fine line here between the wider tyre giving you slight overgearing, and theoretically lower revs at speed, and consequently better fuel consumption v/s the increased rolling resistance actually making the consumption worse....

    Probably would be negligible.
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  4. #4

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    I saw almost no increase in my fuel consumption after going from 155 to 185, so I don't think you will. This was using exactly the same brand and model tyre for both sizes. Your Jetta's pretty light already - it's a TDi

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    Grandmaster jacqvt's Avatar
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    Quote Originally Posted by Fazda View Post
    There is possibly a fine line here between the wider tyre giving you slight overgearing, and theoretically lower revs at speed, and consequently better fuel consumption v/s the increased rolling resistance actually making the consumption worse....

    Probably would be negligible.
    See it's only the width that will differ, the hight and size is the same.

    Just thought the 20 mm will give a better handling on the open road, or am I wrong?

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    Super Grandmaster Fazda's Avatar
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    No you are not wrong, the only thing the width will do is increase your rolling resistance.

    Years ago manufacturers used to publish their fuel consumption figures based on the base model with the skinniest tyres, as they provide less rolling resistance, and consequently better consumption
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    Super Grandmaster ponder's Avatar
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    Quote Originally Posted by Fazda View Post
    No you are not wrong, the only thing the width will do is increase your rolling resistance.


    The girls will agree with that
    entia non sunt multiplicanda praeter necessitatem

  8. #8

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    I actually think it just looks ugly with fatter tyres...
    Narrower tyres FTW!!!



  9. #9

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    I went from 14" to 17" on my jetta 3, Have not noticed any change in fuel consumption.

    What I do have noticed is, there's more grip on the road and it's not so easy spinning the wheels anymore. Which I don't do anyways.

    +1 on the grip. Love it
    Gebore om te kuier, gedwing om te werk!

  10. #10

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    Quote Originally Posted by Fazda View Post
    No you are not wrong, the only thing the width will do is increase your rolling resistance.

    Years ago manufacturers used to publish their fuel consumption figures based on the base model with the skinniest tyres, as they provide less rolling resistance, and consequently better consumption
    So its safety vs consumption?
    DEL PythonFSi

  11. #11
    Super Grandmaster Fazda's Avatar
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    Quote Originally Posted by PythonFSi View Post
    So its safety vs consumption?
    You could put it that way, but it was never an issue with manufacturers...they simply wanted to publish great fuel consumption figures...99% of the owners changed to wider tyres any way, and then wondered why they coul never match claimed consumption figures...those BBS mags look great BTW
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    Super Grandmaster Fazda's Avatar
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    Quote Originally Posted by blaaislaai View Post
    I went from 14" to 17" on my jetta 3, Have not noticed any change in fuel consumption.

    What I do have noticed is, there's more grip on the road and it's not so easy spinning the wheels anymore. Which I don't do anyways.

    +1 on the grip. Love it
    If you go from 14 to 17 with the correct aspect ratio, there probably won't be a difference, unless you are measuring it on all sorts of electronic gimmickry
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    Grandmaster jacqvt's Avatar
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    Well I dont think there will be a much noticed safety difference from 205 wide to 225. The outer size is also the same, so speed wont be affected too.

    But I phoned today just to get a figure on the cost difference, Michellen tyres, 205 R1300, 225 R2000. So hell no, I wont pay that just for a little bit wider tyre. Didn't think it will cost so much more.

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    Safety wouldn't really be much different. Your grip is determined by your downforce not your tyre area. Sure you might have a 10% larger contact patch, but every piece of rubber is 'pushed' onto the road with less force. If you don't 'push' the tyre onto the road, it doesn't grip. Some scenarios might actually be more dangerous with wider tyres. A bigger area means you'll have to displace more water for instance, so your car is more likely to aquaplane.

    A wider tyre would increas rolling resistance, and the slight increase in friction could increase your fuel consumption. Check out a few of the cars used for these mileage test, they usually have hecticly thin tyres.

    Additionally, wider tyres might upset your car's designed suspension geometry, which could reduce grip in certain conditions. If the centre of the tyre is in a different position, you're also likely to put strain on wheel bearings that they weren't designed for.

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    Super Grandmaster Fazda's Avatar
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    Quote Originally Posted by Pyro View Post
    Safety wouldn't really be much different. Your grip is determined by your downforce not your tyre area. Sure you might have a 10% larger contact patch, but every piece of rubber is 'pushed' onto the road with less force. If you don't 'push' the tyre onto the road, it doesn't grip. Some scenarios might actually be more dangerous with wider tyres. A bigger area means you'll have to displace more water for instance, so your car is more likely to aquaplane.

    A wider tyre would increas rolling resistance, and the slight increase in friction could increase your fuel consumption. Check out a few of the cars used for these mileage test, they usually have hecticly thin tyres.

    Additionally, wider tyres might upset your car's designed suspension geometry, which could reduce grip in certain conditions. If the centre of the tyre is in a different position, you're also likely to put strain on wheel bearings that they weren't designed for.
    EXCELLENT Post Pyro...100% behind you on that one
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