Lift Required for 33" Tires on K30?

[Cheng]

It is becoming time to put new tires on my K30 and I am considering a slight increase in tire diameter.

Currently my K30 sits on the stock 235/85R16E tires (31.7" Diameter) and is running stock suspension.

I use my truck for towing and hauling so an offroad style lift is not really an option for me; however at many of the jobsites I work at it can get slick and muddy.

I would like to put on 255/85R16E Mud Terrain Tires (33" Diameter) and am hoping some of you may have done the same thing.

I am thinking that by putting on 1" Zero Rate Add A Leafs like these:

http://www.offroaddesign.com/catalog/Zero%20Rates.htm

And also finding a set of the 5/4 ton CUCV Springs for added stiffness in the rear end that I can run these tires without rubbing problems.

Pictures or advice would be most appreciated.