wheel and tire set up... again

I know this question has been asked 1000 times or more I'm gonna try for myself cause surfin this site  with 3000 non membes and 50 members is slooooow.
I have a 08 Alpha Off road with key n shackle lift. I have a set of mt baja claws 33x13.5r18 (35's just look too big unless you have full sus. lift)
What is the proper offset and backspacing for the 18's? I found a great deal and the wheels are +12mm. and 5.22"

These are the specs for H3 I-5, but I am pretty sure they didn't change the wheels. The websites should help see if it rubs etc...
 
OEM tires:  265/75-16 (802x265mm). Big Hub.
                32 x 10.5 x 16
Bolt OEM tires:  265/75-16 (802x265mm). 
Bolt pattern: 6x139.7 (6x5.5).
Offset: +15 to +35 mm.
Tires up to 842x305mm.
Rims up to 26x10.0".
265/75R 16 = 32 X 10.50 X 16
265/70R 17 = 32 X 11.50 X 17
275/70R 17 = 32.50 X 11.00 X 17
285/60R 18 = 32 X 11 X 18
 
 
http://www.wheelsmaster.com/rt_specs.jsp?item=Wheel-Tire%20size%20comparer&showRim1=1&showTire1=1&sw1=265&ar1=75&bd1=16&rd1=16&rw1=7.5&et1=35&showRim2=1&showTire2=1&sw2=265&ar2=70&bd2=17&rd2=17&rw2=8.0&et2=15&text1=H3%20Stock&text2=Plus%201
 
http://www.dakota-truck.net/TIRECALC/tirecalc.html