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Can I run 245/45/18 on my 740

Discussion in 'Wheels & Tires' started by rsvedell, Nov 7, 2010.

    • Member

    rsvedell

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    Finally purchased a set of style 118's from a 2008 650I. The wheels fit perfectly but I need some advice on purchase of tires. I was looking at either 235/50/18 or 245/45/18. I like the 245 because of the extra tread width. Am I compromising anything by going with 245 instead of the 235 size. Also I like the new BFG A/S tires from Tire Rack. I am retired so most of my driving will be highway touring. Are these prettty good tires? Any help greatly appreciated. Thanks
    • Member

    bcweir

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    What year and model is your 740?

    Tirerack.com has a wheel and tire fitment calculator based on the car you enter in.
    • Member

    CRKrieger

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    You'll do a little better highway driving with the narrower tires. First, there's less aerodynamic drag, so your fuel economy should be (theoretically) better. Second, if you're not cornering near the traction limit, you don't need extra width. Third, you might experience more 'tramlining' and noise with the wider tires, as they have an annoying tendency to do that. Finally, the narrower tires should simply be cheaper to buy.

    I have no opinion on this particular model of tire. I prefer Yokohamas myself. I also prefer NOT to have 'all season' tires on my cars since they're a compromise I'm not willing to accept. If you see any significant snow, you need winter tires, which frees you up to buy dedicated 3-season high performance tires that will be better/quieter on wet and dry surfaces. Since you're swapping wheels off, just get a set of winters for your old wheels and change them out seasonally.
    • Member

    rsvedell

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    I cannot fathom that a tread width difference of .29 inches (9.35 vs 9.64) would make any dramatic difference in mileage. The overall diameter is 2.09% smaller than at 235 tire so the speedo will run a little faster. Other than than are there any other issues you can think of. Thanks
    • Member

    CRKrieger

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    I didn't say it was dramatic. It may not even be measurable, but it is an actual difference.
    I think we pretty much covered it.
    • Member

    rsvedell

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    Thanks all for your help. I did check the tirerack.com for fitment suggestions but due to the diameter difference it was not included in their recommendations.

    I finally chose the new conti dws in a 245/45/18 and had them installed yesterday. First impressions lead to easier steering, extremely quiet ride, nice comfort, and very quick steering response (got cut off at 45 mph - quick manuever required) leading to car feeling like its on rails.

    Road force was a low a 9 lbs with one tire needing no weights at all... Amazing.
    • Member

    bcweir

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    On a hot day, at moderate to high speed driving....

    ..........heat expansion from the friction of the tires contact with the roadsurface probably changes your tire measurements even more than that.

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