On the left coast we have mile markers on the highways. Simply drive the truck on the freeway and look for a marker. At 60 mph, it should take you 1 minute to get to the next marker. Bring a stopwatch. you can also check the accuracy of your odometer. I think a variation of + or - 5% should be acceptable. If you have any doubts, take it to a speedo service center.
I use the calculater on
www.4lo.com. Me thinks you used the rim size, and not the tire diameter...Most 16 inch wheels will have a tire diameter of about 30 inches.
Unless you have overdrive... transmission ratio will be 1 in your top gear. if you don't have 4wd, transfer case ratio will be 1
