Re: re:Tire Sizes - Help for the math impaired

["Csank" <csank@domain.elided>]

OK Dug,

So, the 165/80-14 has a width of 165mm and a sidewall height of .80 x 165mm,
which is 132mm.  Multiplying by two gives 264mm.  Dividing that by 25.4
gives 10.4.  Added to 14, this is 24.4"...right?

The 165/82-14 (as noted by Carl Newcomb) has a width of 165mm and a sidewall
height of .82 x 165mm, which is 135.3mm.  Multiplying by two gives 270.6mm.
Dividing that by 25.4 gives 10.65.  Added to 14, this is 24.65"...right?

And the 185/70-14 has a width of 185mm and a sidewall height of .70 x 185mm,
which is 129.5mm.  Multiplying by two gives 259mm.  Dividing that by 25.4
gives 10.2.  Added to 14, this is 24.2"...right?

So, whatever way you cut it...the calculators are right...and Paul Mitchell
was wrong.  The 185/70-14 sizing pretty closely proximates the original
165-14 size (certainly more than we were led to believe) as found on many of
the 105 series cars with the ATE brakes (1969 - 74 approximately).

> multiply the width of the tire by the aspect ratio w/a decimal point in
front, to get the height of the sidewall.  ie:  my 225-50-15 has a width of
225mm. it has a sidewall height of 0.50 x 225mm, which is 112.5mm.
>
> as the total diameter of a tire includes *two* sidewall heights, yust
multiply that by two; then convert it to inches by dividing it by 25.4.  so,
the 112.5 times 2 goes back to 225; divided by 25.4, it's 8.86".  add this
to the 15" diameter & ya get the total tire diameter of 23.86"
>
> hth,
>
> someone e.

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