If the truck is in 2wd it doesn't make a crap what size tires are on the front. Autotrack doesn't automatically engage your transfercase if you're slipping when in 2WD - it ONLY engages when you select the mode "AUTO 4WD".... :nutz: its a screwy setup but works good at slow speeds on slick roads, other than that... worthless. Pretty much a soccer mom 4wd option to make them feel better when driving in crappy weather.