harder tires would be better than softer tires.
as also mentioned in other posts... tire pressure plays a role in mpg's too.
yes, lighter rims could help. less rotational mass for starting off the line & highway driving.
dont go wider than stock tires, as that can create more drag.
someone had mentioned hypermiling, its a hard concept to keep up with. also much better for smaller cars, but the principle can work on bigger vehicles too.
as far as air filters, i like the dry ones better. less mess & you wont have to clean MAF as often.
especially if you accidentaly got heavy on the oiling after cleaning the filter.
but be realistic, you have a big SUV w/ a big motor, not a prius
window sticker for your ride shows combined mileage of 13. 12 city & 16 highway
mileage will also change w/ the time of year, depending on winter vs summer fuel mix.
i may have missed it, but another user inquired as to if you had AWD. so what is yours 2WD, 4WD, or AWD?
if you dont have window sticker, you will want to look up build codes & figure out what differential gears that you have.
along w/ how you usually use your vehicle. daily driving, flat/hilly roads, towing, etc.
all that comes into play when you want better mileage.