Removing brake roter

Need to know how to take off a door panel on a kia amanti

Hello! I just bought a 1997 Nissan Pathfinder. Now, I do realize this is an SUV, and they are not gas savers. I asked the salesman about expected mileage, and was told to look for mid-high teens in town, and high teens to low 20s on highway. I am getting 12. (12.2 to 12.7 to be exact, with about 50/50 city/highway driving). I have checked online, and it looks like I should be getting much better than that according to other pathfinder owner's claims. It is running exceptionally well, but here are some things that I'm sure are cutting the efficiency down: It has wide all terrain tires on it...31 X 10.50 R 15 LT It has a large chrome brush guard across the front It has 4WD It does have dark tinted windows, and it's white, so AC doesn't run as much. It does have OD. I like the looks of it, but I'd rather have some MPGs. I am thinking the tires are the main culprit. Is this correct? How much do you think these tires might be affecting my economy? If it's minimal, I'll live with it, but I really want to get the average economy out of this thing. It came with a K&N air filter (which I'm not convinced is the best thing, but it's on there). I also considered buying a "Tornado" type intake insert that claims better performance, mileage, and less emmissions. Anyone have experience with one? I've heard good things, but I'm skeptical of a gimmik too. I also plan to use synthetic oil in the engine and the transfer case and differentials if this would help. Can you use synthetic in a limited slip differential? I'd like to keep the ride, and if I could bump my fuel economy up about 5 mpg, it would be in the range of other SUVs, and I'd feel much better about it. The way it is now, I feel like I could trade it for a 4 runner or most any other suv and get better mileage. Sorry for the lengthy post. Any helpful input would be greatly appreciated.