On Thu, 29 Sep 2016 06:59:52 -0400, "David L. Martel"
wrote:

Paint,

With larger tires your speedometer will read slower than your actual
speed. To make a calibration table for the larger tires find a measured mile
and record your speedo reading and the elapsed time.
Also, 15 " tires fit a 15"rim. The diameter of the tires not the rims
should be measured.

Dave M.

My little Ranger came with puny tires on 14 inch rims. The speedo was
pretty accurate. I switched up ro large (225/70 summer and 235/70
winter) X16 tires and wheels. My speedo is very accurate with the
235s. The secret? Replace the speedo gear with the correct one for
the gearing and tire size.