Go big.....REALLY BIG........(see photos below) That's what 20X15 rims look like. Yes that is a full size 2005 GMC Sierra bed that they are in.
Then contact Micky Thompson and get the fattest tire made. This car has a lot of real estate if you know what I mean. To make a tire look fat on this car, It's got to be REALLY fat! Then go as low as you can. Anyone know what makes a car look low? A veteran of the industry told me once " a good rule of thumb is to get the top of the rim within 1" of the wheel well opening." In most cases, the car will look super low even though the ground clearance may be great. Try it once and see!! In some cases like a 55 Chevy, no problem, with my car it is super hard to accomplish without modifying the wheel well openings.