Jeffrey Misner wrote:
>Stock P235 75R15's = 28.8779527559.... inch diameter.
>P245 60R16 = 27.5748031496... inch diameter
>P245 50R16 = 25.6456692913... inch diameter
>P245 65R16 = 28.5393700787... inch diameter
>P265 60R16 = 28.5196850394... inch diameter
>P275 60R16 = 28.9921259843... inch diameter
>
>If you _Really_ want a 50 series tire, you'd need a set of
>P325 50R16 = 28.7952755906... inch diameter
I see that Rob's truck is a 2WD, though, which means that stock is:
Stock P215 75R15 = 27.7 inches
The 235/70's he has now come out to 28.0 or 29.0 (I forget if they were
on 15's or 16's).
For stock height, he's now looking at a set of
P295 50R16 = 27.6 inches or
P245 60R16 = 27.6 inches.
I wouldn't worry too much about matching the stock size exactly, though,
because your speedometer is inaccurate anyway. Put your tires on, get
out your stopwatch and your calculator, and figure out how fast you're
really going when the speedo says 65.
Later on, Russ wrote:
>i believe a 245/50 would be your best bet for the height you are
>looking for...but the truck will ride harder since you won't have
>hardly any side wall.....
True to a point. As y'all know, sidewall height is roughly the tire
width times the aspect ratio: 245 x .50 = 123 mm = 4.82 inches. Stock
is 215 x .75 = 161 mm = 6.34 inches. What this means to you and me is
that a wider 50 series tire may have a sidewall height similar to a
narrower 60 series tire. The shorter sidewall will ride harder but
handle and stick better in corners.
I said "roughly" above, because these numbers are far from exact,
varying widely between tire manufacturers and models. The only accurate
measure is getting circumference or diameter numbers from the
manufacturer. And then the numbers change as the tire wears. That's
why I only went to three significant digits in the numbers above.
Finally, as sidewall height comes down, rim width becomes increasingly
important, as the shorter sidewall can accomodate a smaller range of
wheel widths. That's why a P235 75R15 will fit the stock 6 inch rims
just fine, but a 235 60R15 would be too wide for the wheel. Again, the
range of wheel widths a given size of tire can accomodate varies widely
by tire manufacturer and model, and the only way to tell for sure is to
get their specifications.
Nothing is ever easy, it it?
- Paul Schelling
SchellinPM@corning.com
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