tire size

[MarineHawk]

Originally posted by shhrtbs:
instead of a paint strip, i used a chalk mark, and did the math. just wanted to know if anyone had other ways to do it.

I assume that the chalk/paint method is the most accurate because it measures the actual radial length of your tire (diameter x Pi) when actually driving it. When measuring the diameter directly, you might get pretty close, but you have to guess a little about where to measure and whether or how much the top of the tire will compress under load.

Another way to do it is to zero a trip odometer as you pass a mile marker on a fairly-striaght highway; drive, say to 20 miles; as you pass the 20th mile-marker; see what your odometer reads. If, for example, your odometer read 19.5 mi, your speedo and odo are reading 2.5% too low, meaning that your tires are 2.5% larger than the size for which the DIC is programmed.