Cognito is great stuff, but 1/2ton trucks axles don't like anything over a 35" tire. I ran 35's on my Suburban for years, added 37's and the first time off-road I broke a rear axle. All the off-road magazines say don't run a tire over 35" with a 1/2ton truck. Also IMO if you go to big with your truck and tires it starts looking like a swap buggy.