what backspacing?
 

so im puttin 38's on my 05 and getting new 18's with 9 to 10 inch width....i want my tires to stick out about.....3 inches....so what backspacing would i need to get. Im pretty sure my stock wheels have 5.5 BS and i was thinking mabye i should use lik 4 5/8th's or 4.5???

That will definatley make them stick out a lot. Personally, I wouldn't go with a wheel with less than 5 inches of backspacing.