No better way to learn than by asking.
The way it works, generally, is like this: an engine which idles down the strip, showing off, doesn't work very hard. Therefore, all other things being equal, it is cooler inside than one which has a full load of firewood, blasting at full throttle up a steep grade. Given that a certain temperature flashes(ignites) your air-fuel mixture, the one which is working harder needs less of a spark - or, to put it another way, a cooler spark - to bring on the flash.
A 205/75 has a pretty low tread height. Take a look at this:
[IMG]http://inlinethumb50.webshots.com/40497/2252603640096215731S200x200Q85.jpg[/IMG]Granted, my chassis is heavier than yours, but the fender wells are the same, and if you ignore the number of wheel nuts, this gives you an idea how my tires would look under your truck. And, you'll like the speed improvement.
