Need Help w/ Lift and Tires

[mothertruckr]

So, Im trying to figure out what lift tire combo to go with and before anyone says anything about where the search bar is... I already have been doing a lot of research and still need help.

I have an 07 nnbs GMC Sierra 1500 4wd right now it has 275/60r20 factory 20" rims
Guy I bought it from said it had a 3.5" leveling kit? Looks to be more than that to me. heres some pics:







That block in the rear measures 3 inches and the truck looks level.
The tires it has on it have plenty of room...
the tires i want to get are the bfg KO2's in either the 35x12.5r20 (preferred cause its cheaper) or the 285/65r20... both are a 35 but the 285 is 1 inch narrower

So will the 35's fit?
Do I need bigger lift?
And longevity of everything, if my current set up is shortening the life of my cv axles for example, I would want to switch to something with better geometry.

on a side note the truck will almost always be road driven, Im in college and dont plan to tear up my only vehicle by going mudding, but I have always preferred the ability to go offroad when needed via storms or other scenarios. Where I currently live in florida it floods every spring and I have frequently had to drive through a foot deep, or more, of flooded roads to get out of the city and to higher ground... or like two years ago with my lifted duramax I spent half the day pulling out stuck and stranded vehicles. AND where I might be moving to next year can get a foot or so of snow on the regular. So I definitely want taller than factory height.

Thanks in advance for any help

[4x4k30]

I would say that you should be able to fit the 35s ok as long as you stay with a wheel no wider than 10. post a pic of your truck maybe can tell more what it looks like and what you can as far as running bigger tires

[mothertruckr]

Originally Posted by 4x4k30

I would say that you should be able to fit the 35s ok as long as you stay with a wheel no wider than 10. post a pic of your truck maybe can tell more what it looks like and what you can as far as running bigger tires

I actually noticed while taking the pictures, the front has the norcal mod in the fender wells, so maybe a previous owner was running 35's already

[4x4k30]

Originally Posted by mothertruckr

I actually noticed while taking the pictures, the front has the norcal mod in the fender wells, so maybe a previous owner was running 35's already

yea it looks like there is room with the fender mods I know that you could run 33s for sure. the 35s you will probably need to trim the front air dam some for sure I have 04 2500hd with a 6inch lift with 37/13.50s on 20x12 wheels it works fine with 35s but with the 37s I had to do a lot of trimming on the air dam and front bumper and rear of the front fender had to be trimmed so I know you don't want that with the nice truck you have .I am more into the older trucks so I don't know alot about what will fit and wont just trying to help.