So I have an 06 lariat super crew 4x4. I want to get a leveling kit on it but then I want to put some nitto mud grapplers on it. What size tires would I need? I have the 20 inch rims

 

The search function is your friend. Try this thread there is a lot of good info here:
https://www.f150forum.com/f4/tire-wh...04-08-a-24510/

 

Here is my truck with a 2.5" level, 18" wheel with -12 offset and 295 Nitto Trails.

 

Looks good max4! Did you have any rubbing?

 

A little. Just had to trim the plastic on the corner of the bumper and about a 6" square out of the plastic in the wheel well. No metal trimming. Turned out better than I had imagined! Thanks for all your help too!

 

2.5 level and 305's

 

I've also heard about having a 3" rear block too. What difference does that make?

 

It would keep the nose down look on your truck and You wouldn't be gaining any tire clearance because your front end will still be the same height as if you just leveled it. I run 33 inch tires and never have experienced any rubbing. I could probably clear 35's with no problems at all.

 

Thought you just said you wanted to level it ???

 

Yeah I do, I've just seen other thread posts about having a 3" rear block too. I just want to get enough clearance to get 35" tires