Couldn't find that chart but I did find a tire size calculator which confirms that my way of thinking is correct.
180-75-13 original to 225-75-14 should make the speedometer read slow by about 10 percent. I.E. reading 60 mph should be actual speed of 66 mph.
I think this makes it obvious I have the wrong gear in the tranny. Anybody know which gear I would need and where to get one?