How much lift would it take to clear 40's. I want to run 39.5 boggers or 40 Ground Hawgs. 456 gear or 488 be better.

 

I'd say at least 9-10" if you don't want them to rub, I run 37's with 6" and I can rub just a tad if I compress the front with the wheels turned. 4.56's should be good with the diesel.

Is this a pavement queen or are you actually gonna wheel it?

 

I have 38's with 8" and have LOTS of room, but with 40's your probably gonna need at least 10" Mine's a pavment pounder/ tow rig.
I've been looking into a gear swap, I was thinking around 4.10's (3.55 now) I use this truck as a commuter so if I get any lower I'll loose what economy I have. Sure would be nice to have just a smidge lower gearing.
Dan

 

My sig says I have a 9" lift (7" sj with a 2" space)but its a couple inches less because of my coils sagging but I still clear the tires fine and my front end is moved an inch or so forward. I can flex all the way with no rubbing.

 

With the wheels turned?

 

Another thing to consider is the "actual" tire height. A lot of 40's are only 38" - 38.5" tall.
My 37" Goodyear GS-A's were only 36.2". But my 37" Cepeks are 37.1".
Tread width will come into play sometimes more than height. Plus the width and offset of the wheels.
The 37" Goodyears, 12.50, 16.5" on a 8.24" wheel never rubbed with a 4" lift.
The Cepek Fun Countrys, 13.50, 17" on a 9" wheel rubbed bad.
Had to go up 2" more to clear. The extra 1.75" of tread width didn't help matters either.

Brad

 

I got 40s. 6 inch suspension and 3 inch body. my tires hit the rear of the front fenders when flexed and turning, but I hope to be remedy-ing that soon.

 

Yes, no rubbing at all....ever.