[Zoomad75]

Congrats on the k5 buy. As far as the lift goes, 6" will provide pleanty of room for 35-36" tires without any cutting. Then again, I'm running only 4" on mine and run 35's and had zero rubbing. This is just my personal opinion, but I like running the lower lift amount with the 35's as it limits the topheavy feeling you get the higher you go. The type of wheeling I do has us up in the mountains of Colorado some of which are on high shelf roads. You don't want to be overly top heavy up there for sure. Plus, on the street it doesn't feel like it's going to tip over when going around corners. Again, it's personal prefrerence. The other thing to look at between 4" and 6" lifts is the amount of mods needed to correct for the lift. (steering and driveline) Most 4" lifts need at least a raised steering arm, but don't always require driveline correction. Meaning less money to finish the lift right. 6" lifts will need a raised steering arm plus a dropped draglink for steering correction. The 6" lift might need more driveline correction in the rear due to how much steeper the rear driveshaft will be sitting. Some have got away with just wedge shims to the axle to correct pinion angle and others have needed to add a cv joint to the front of the rear shaft. It varys by truck.

As far as kit's go there are a ton out there. Top of the line is BDS or Deaver (read $$$$$). Less cost, but with nice soft springs are Tuff Country. Superlift has them, but with a higher spring rate. The most economical kit is probably rough country, but they do have a higher spring rate so the ride is stiffer than the soft springs. If you shop it right though, the Rough Country kits come in with everything needed, springs, shocks, hardware and a rasied steering arm. Most of the other kits make you pay separately for steering correction. I've got Rough Country springs up front and a shackle flip out back. I don't mind the ride at all. Plus off road my tire pressure gets dropped to 15 psi and it provides an extra level of softness to take the edge off of the rocks.

One thing to keep in mind on the tire size though. Gearing. You asked whats the size to run with no to minor mods. You need to figure out what axle ratio you have. 35's will require a deeper gear (higher numerically) to keep the engine/trans running in the same rpm range at a given speed. If your running what was most likely stock ratios of 3.08 or 3.42's, tires as big as 34" and up will make the truck run like a dog. If you have 3.73's it will be better, but still not optimal for 35/36's. I'm running 35's with 3.73's and it is ok, but I have to dig into 2nd or 1st gear when climbing long steep mountain hills on the highway. Off road, it isn't as bad since I've got a 465 manual trans as granny gear and 4low make up most of my lack of axle gearing. Ideally 4.10's what you really want for 35's to get the best of both worlds, on road and off. 4.56's adds power but your engine speed at 65 really starts spinning fast.

If you got saddled with sucky gearing you might not want to go bigger than 33's or else I'd be spending money to regear both axles if you want to run 35's. If you got a 700r4 trans it would wise to regear if going bigger. Those trannies don't survive long if the the tire size and axle gearing arent optimised.