Tire & Wheel Question

[johnnyz71]

I wasn't thinking about putting wheels on my truck, but I stumbled across a local craigslist ad which has gotten me thinking. The wheels are 20" Incubus Alloy Krawler (black) with Nexen 275/55/20 tires. I know that the black will look good on the white (I used to have 24" Boss wheels on my '07 Suburban Z71 and it looked awesome) but I have no clue about the company Incubus or Nexen. Are the tires good tires? What is the largest tire size in 20" I could go without rubbing or scraping? I have a RC 2" lift in the front and stock in the back. I don't want to add any more lift or level kits. Will the 20" look too small on my current set-up?

 

The other thing is that if I keep the stock wheels (and don't put on any aftermarket wheels), I am going to get bigger 18" wheels and then sell my Duelers on craigslist. What is the biggest size 18" I could go without rubbing?

 

Here is a link to the 20" wheels:

 

http://www.discountwheeloutlet.com/product.php?id_product=72