I think checking our egos and buying tires that really reflect our driving needs would definitely help our gas mileage
Macho attitude is very expensive in many ways, including (gas) mileage.
I can't avoid rain, snow, and ice; but I could avoid most mud. I don't need to off road at all, except my cousin's nasty long steep rugged driveway, but all season tires could handle that.
I really only need all season tires for transportation, but I sure love my Cooper AT3 for hobby offroading.
This is one reason I run 30" ATs these days instead of 33" MTs like I used to. I'm getting wiser, more conservative, and more realistic with age.
There was a young guy in another thread awhile ago who claimed that 35" MT don't affect gas mileage enough to matter (compared to a smaller tires), and he claimed he needed 35" tires to guarantee he could get home everyday. I called B.S. on that, and flames ensued. Some people are morons. If he showed up spouting that baloney in this thread, I wouldn't say anything because you guys would beat me to it.
There's nothing wrong with running big tires if you want, but it affects gas mileage (a lot). Likewise with aggressive tread.
The older I get, the smaller and less aggressive my tires get.
Having tried an assortment of tire sizes and levels of aggressive tread over the years, I conclude that I want/prefer 30x9.5R15 AT for fun, but I could get by just fine with a 225/75R15 all season tires, if I'm honest with myself.
I really don't even need a Jeep. I could get by fine with my Buick. However, my XJ gives me a second car, which is useful, a lot of fun which I need, and it allows me to (someday) switch my Buick from snow tires to touring tires, which will help the Buick's gas mileage. So my XJ makes it possible for my Buick to become a better hypermiler.
I need two cars so I can drive one while modding the other. It's near impossible to do much mods on an "only" car. A spare car is needed while modding the other car. So I do need my Jeep! Ha! I'm keeping it!