need specific help with rim sizeing and offset

Hey thanks,

Im really having trouble understanding the tire sizing terms and measurments hope you guys can help as i am really trying to place an order but im really unsure about sizes.
I am looking to purchase kmc xd monsters 18" with a 5 inch offset (when i say off set, in my mind it means the more the wheel will stick out from under the fender flair. not sure if thats accurate) i have a toyota tacoma with a toyotech 3'' lift and a 6 on 5.5 lug pattern im looking to get about 2 inches to hang out from the fender flairs.the tire i was thinking of going with are 33'' pro comp xtreem allterains ( this is the second measurment i allwayse get confused about. why do the sizes turn int like 295 ext. then go back to just saying 35" is there a way to read thies sizes to determin the hight of wheel? please let me know) could you please set me up with what rim and tire size i should go with and most importantly the right off set so i can order thies things and stop clicking away at my keyboard getting more and more confused every night. really hope you can help thanks

Kevin-