I have been looking at fitting 285/75/16 to my Navara and during the search for info I came across this. It may have been posted before, I thought it was great giving the rolling diameter and speed comparison.
http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
cheers
NICK
http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
cheers
NICK