[themustangkid]

im replacing the stock 14 inch wheels on my '68 with some 16 inchers. a friend told me that th new wheel diameter would mess up my speedometer reading. is he correct? if so, how do i go about correcting the issue? (so i dont get too many tickets )
if its of any use to know, i have an auto transmission and a 2.79 standard diff.

thanks a bunch!

[OrangeCrush]

It all depends on how big a difference in diameter you have. If the diameter is only an inch more you will only be off by a few mph. There are formulas online that will give you the correct number of teeth for your speedometer to read correctly. Just plug in the variables & you will have your answer.

[rocky289]

When I went to 15'' on mine I used tires that were the same diameter as the original crossply's. I have since checked the speedo reading against a GPS & found it to be spot on.

[dodgestang]

Originally Posted by themustangkid

im replacing the stock 14 inch wheels on my '68 with some 16 inchers. a friend told me that th new wheel diameter would mess up my speedometer reading. is he correct? if so, how do i go about correcting the issue? (so i dont get too many tickets )
if its of any use to know, i have an auto transmission and a 2.79 standard diff.

thanks a bunch!

To reiterate/reinforce previous comments.

You're friend is correct if you do something like put a larger outer diameter TIRE on your car (or smaller diameter).

You're friend is incorrect if you do the smart thing and downsize the sidewall on your tire as you go up with your rim size. For example....215 60 15 versus 215 50 16