I've verifed it with GPS, and radar. It's only about 2-3 MPH off.
Per this thread https://www.cherokeeforum.com/f2/wha...-65217/index2/
It seems i should be getting more.

Highway miles are not much better (if at all) than city with a 4.5" lift. That's a lot of height=a lot of drag at highway speed. Sorry if this was already said.

I'm just curious as how some people with lifted XJ's can get 15 mpg on 33" tires. I'm on 32's and I can't even come close to that. Just seems like there's something wrong here, I just can't figure out what.

Could be because you have stock exhaust? Could be were your location ? there are so many things...

And that's exactly what i'm trying to track down. I don't really want to throw money at it on things that it doesn't actually need.

maybe its time for a exhaust upgrade ?

Yea, I might do that. Like i said though, when I checked everything with the diagnostic scanner, the o2 sensors status said "ok", and everything else said "ok" however when it came to the catalytic converter it said "inc". Anyone know what that might mean?

i get 18 mpg on 32.11.50 and 4.5" lift, flowmaster exhaust, fuel filter replaced, o2 replaced. plugs wires and dist cap and button

this is really the only person who's got it right so far. Without a calibrated speedometer and proper gearing you're not going to "see" better MPG.

As far as what you read in other threads and hear form other people running simular setups, you don't always get the truth. And driving habits can also play a big part, as well as weather, road conditions, drivetrain conditions, and the list goes on. Start with the Speedo-gear swap as it is pretty cheap and easy to do. Do your research and make sure you get the right one and measure the exact circumfrence of your tire with the proper tire pressure in it.
To get a good measurement mark the ground and your tire and then roll your vehicle until that point on the tire come back down to the ground- mark a second point on the ground. Measuer the distance between the two marks and this will be the circumfrence of the tire.

I'm running 31 x 10.5 x15's on one jeep I own with a 3 inch lift, my other jeep is the same only stock height,with 215/70R15's wanna guess which one gets almost 21 mpg and which one gets 11.5 mpg? Give you a hint it's the more fun one to drive that gets crappy milage,lol

If those are both XJs that you own you might want to check that stock tire size, cause 215/70/15 is on the small size. According to my information the stock size should be 225/75/15.

I have 33's on a 6.5 lift and am getting between 13 and 15 MPG in the city. Ive only have my jeep for a yr. It's a 2000 and only after market performance is exhaust.

Do a aftermarket exhaust, with a high flow cat, and new upstream o2 sensor.

The inc, means the test is incomplete, means one of two things, u either dico the batt latley, or the cat is bad, and is taking to long to set the readiness monitors.

You should without a doubt change your gears, even with 31's they recommend 4.10 gears for power and gas mileage.

But like everyone else says, stock gears and those tires, the under 15mpg estimate is right on the money, literally...

You can try the o2 sensor, but you're not going to see a 5+mpg increase from that. It really has to do with your gearing.

Last recommendation would be to check your air filter, switch to an electric fan, and maybe pull the AC if you are still getting poor mileage.

Let me know if I am wrong, but this just made up my mind to stick to 31's.

This is what makes me wonder. I'm not saying i should be getting 18mpg, but an 8mpg difference is too much. Do you have stock gears?

Same question, do you have stock gears?

I understand there's a difference. My tires are 10% larger then factory (according to online calculators). So, if my ODO says i've gone 300 miles, i'm really going 330. If i use 30 gallons of gas, according to my ODO i'm getting 10 mpg, but i'm really getting 11. So, really...i'm getting about 11. Still doesn't make sense though, should be getting more then that, especially mostly highway.

I'm not saying you're wrong. I understand i need to change gears, etc. However even with stock gears, my MPG shouldn't be THIS bad.