Changing tyre sizes
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  1. #1
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    Question Changing tyre sizes

    Hello all,

    I'm a fairly new owner of a BMW and loving everything about it so far. As it is coming up to winter, I don't want to be the butt of everyones jokes about me getting stuck in the snow.
    I have checked a few websites for replacing my current summer tyres for winter ones but seem to be struggling to find my choices for my rear size. My rear tyres are 245/35/18. I can only seem to find Pirelli's in this size and are also coming in at 340 each!! Change the size to 245/40/18 and the options are huge and the prices drop significantly to sub 100.

    Has anyone tried changing the tyre size and will it make any difference? I understand there will be a percentage difference in speed.

    The front size 225/40/18 are very reasonably priced so would keep these as they are.

    Any suggestions or comments from people who have done this before would be greatly received.

    Thanks

    Andy

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    Quote Originally Posted by anderoush View Post
    Hello all,

    I'm a fairly new owner of a BMW and loving everything about it so far. As it is coming up to winter, I don't want to be the butt of everyones jokes about me getting stuck in the snow.
    I have checked a few websites for replacing my current summer tyres for winter ones but seem to be struggling to find my choices for my rear size. My rear tyres are 245/35/18. I can only seem to find Pirelli's in this size and are also coming in at 340 each!! Change the size to 245/40/18 and the options are huge and the prices drop significantly to sub 100.

    Has anyone tried changing the tyre size and will it make any difference? I understand there will be a percentage difference in speed.

    The front size 225/40/18 are very reasonably priced so would keep these as they are.

    Any suggestions or comments from people who have done this before would be greatly received.

    Thanks

    Andy
    What bmw have you got?

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    Quote Originally Posted by anderoush View Post
    As it is coming up to winter, I don't want to be the butt of everyones jokes about me getting stuck in the snow.
    No need to be, it's not what you drive it's how you drive it. A RWD needs winter tyres no more or less than FWDs do.
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    To answer your question - just do it. Your speedo will be 3.82% 'out' but it was probably never 100% accurate anyway. 653mm diameter versus 629mm.

    If you had a 4wd car I'd be more hesitant, but this... no.
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    Quote Originally Posted by Devil View Post
    What bmw have you got?
    116d M Sport auto

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    Quote Originally Posted by cforehead View Post
    To answer your question - just do it. Your speedo will be 3.82% 'out' but it was probably never 100% accurate anyway. 653mm diameter versus 629mm.

    If you had a 4wd car I'd be more hesitant, but this... no.
    That's what my feeling is towards it. You're allowed a few mph grace through the speed cameras anyhow so will just bare that in mind.

    Thanks for your response!

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    I changed my 245/35/18 to 255/35/18 loads more choice and they fit perfectly. Just to add my Speedo is now spot on.

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    Link to tyre size site.

    http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

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