On 2010-09-17, Don Q <Don> wrote:
> On 2010-09-15 09:29:30 -0400, Arye > said:
>
>> It's true that that 185 and 195 indicate the tread width. However, the
>> 60 indicates the ratio of diameter to width, so it goes up
>> proportionally.
>
> Strictly speaking you are correct of course.
> However, 60% of 185 versus 60% of 195?

(195-185)/195 = 5%

> Without going into heavy (for me) math, I will speculate that the
> difference in diameter will come to about 2%. If I'm going 51 and my
> speedometer is showing 50, I can certainly live with that margin of
> error.

Using stock tire sizes, my speedo is off by 8-10% at freeway speeds,
so a 2% correction is hardly worth considering. A 5% correction is
a little better.

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Grant Edwards grant.b.edwards Yow! What GOOD is a
at CARDBOARD suitcase ANYWAY?
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