On a stock truck tires leaning in at the top simply means the springs are sacked so the fix is easy... get new springs. But since you have a lift your springs are not stock so you will either have to get a custom set of higher rate springs or modify the lift by install shims under the springs you have or raise the arms to correct the front end geometry. This applies to coil spring front ends only. If the truck has a leaf front end then you could simply add a leaf to increase the overall spring rate.