tire size

Would changing tire size from p195/75r/14 (factory) to p195/65r/15 change tire height? Thus putting my speedo out by 12mph

www.4lo.com (http://www.4lo.com)

Nice. the 14 is a 25.5 inch tall tire, the 15 is actually a 25.0 inch tall tire. So you're speedo would read slightly faster than your true speed.

What has tires this small? my donut spare is almost that big!

Yes the 195 is the width from bead to bead in mill. the 75/65 is the percentage of sidewall and that does not change with rim size so the tire is larger. 12 mph larger though? i would'nt think so but mabey.

Contact the manufacturer of your rim/tire and they should be able to tell you. With the purchase of a programmer, depending on your year, you can calibrate your computer according to the size of the tire/rim, etc. Also, if you go to a ford dealership, they can calculate it and give you a different speed gear for the transmission that will correct the problem. The speed gear is not all that expensive.
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