1.5 is dead level-I am running 37s but tire size does not matter. Ran my Gen 1 at mid perch also level and collars on my Gen 2-used Icons as I needed 2 1/4 to make level. The Icon Gen 2 collars were adjustable. Pics can be very deceiving on showing you the true stance. Best to use measurements. Check your starting point so you know what you need. I will say that if you put a lot weight in the bed, you will be nose high which should make sense given the starting point. That said, one of the weakest parts of a stock Gen 3 is how soft the rear springs are. Rear is much better vs leaf springs but a slightly more stout set that lets you load a couple hundred pounds in the back for spares or other gear is needed and I am sure being designed/made now or real soon.