Hi folks (I posted this in the OEM forum by accident)

I have a 2000 4x4 xcab stepside V8 that currently has the following combo:

305/45/22 Nitto 420S tires on Centerline wheels. The tires stand about 31.5 inches tall.
What I like: This combo fits in the wheel wells perfectly and does not stick out on the side of the truck. The tires are just about perfect width. I like the look of a large wheel.

What I want to change: I am going for a bit more off-road capability so I would like more tire (bigger sidewall) and less wheel but still want the overall 'space and placement' of the current setup. I was told that the wheels I have now are no longer being made so if I hit a rock and mess up the wheel, I am in bad shape. Plus I don't think I could fit a bigger sidewall tire on the 22 inch wheels without lifting the truck. I prefer to not lift the truck - it sits just right the way it is - any off-roading I do will be mild - nothing crazy and a little mud thrown in on occasion. I plan to ebay the wheel/tire set I have now.

I know I will need to go to 20's or 18's for wheel size to get the bigger sidewall without rubbing, etc. What I am clueless about is stuff like offset and backspacing. I don't want the wheels to stick out from the fenders.

What combination of wheel tire can I go with to achieve my goals? It seems like a 305/18/70 or 305/20/60 would be about right or something like that. Should I ask for 'stock backspacing, etc. to insure they will fit nicely in the wheel wells? If you need some pics, I can take some and try to post them on here. Any general comments on this are very much appreciated and also any general comments about the ins and outs of selling wheels/tires on ebay would be helpful.

Thanks