This is a fantastic tire and wheel size calculator/comparator:
Just plug in the values from the two tire sizes and it will give you dimensions
and recommendations for the second set of tires. According to the site, the
second set of tires will be almost 1" wider and about 1" greater in diameter
than the tires on the car; there is also a warning that the larger tires may
Whatever you do, look at the date codes on whichever tires you put on the truck
to make sure that they're not too old to safely use.
John P. New
London, Ontario, Canada
On Monday, October 8, 2018 4:02:23 PM EDT Peter Murray wrote:
> In cleaning out the garage/shop of my recently-deceased father-in-law, i
> ran across two pairs of P215/70/R15 tires. They're bagged and unmounted,
> and appear to be in similar and reasonable shape (about 50% tread
> He also had a 1969 Ford F100 pickup that has been sitting for a while. The
> tires are pretty beat and one will not hold air. They're 235/75/R15. I got
> it running while I was out there last week, but with the one rear flat, it
> was tough to evaluate it much. Electrically it appeared solid. I drove it
> about 100 feet, so the clutch, first and reverse all worked fine.
> I realize they're not quite the same size, but I wonder if I couldn't
> replace the tires currently on the truck with the four unmounted tires. I
> realize they're slightly different in width and circumference, but they're
> pretty doggone close. This isn't going to be used as a hauler. More likely
> my mother-in-law will sell it (sigh), and I figure that having four decent
> and inflated tires gives a better negotiating position than requiring a
> buyer to tow his purchase away...
> Aside from aesthetics and (slightly) incorrect speedo/odometer, what Bad
> things could potentially come from putting these tires on the truck?
> Yes, i would probably try to keep it, were it not 2000 miles away (its in
> western Colorado, I'm in northern Virginia) and my 3 young children and my
> self-employment keeping me busy enough.
> Thanks for all your sage wisdom!