So I just got back into a truck yesterday, purchasing a 2008 Silverado ext cab 4x4. Much to my surprise, it has the 20" tires on it. My old one had the standard 265/70/17. This has the 275/55/20. So other than the obvious that it's a larger tire (and I understand what the numbers mean), what really does it mean? The tires are more of a road tire than an off-road/AT tire. How much worse is my fuel mileage, does it drop my take off ability, anything else that you can think of? Thanks.