A month ago was tune up, new O2 sensors, blow out the rear cat. I'm not sure where the bump in gas mileage came from but I also changed tires to something I bet no one else is running.
I've had mostly 33s, plus the original Rubicon Goodyear MTRs, plus a short stint with 35s. I never checked mileage with the 35s, I just knew it was bad. Never cared what the factory tires delivered cuz I wanted 33s. But I've never hit 20mpg, even running down the gorge to Portland at under 60mph with 33s.
For the past month with the new skinny 7.50R16s, pulling a trailer thru the mountains and holding 60mph plus passing all the trucks on the 3 lane grades at 75mph with a 1500# trailer, I got 14mpg over 300miles. For the next 300miles I held back averaging 55mph but never over 60mph. With the trailer I got 18mpg.
This weekend was 600 miles, no trailer, average 60mph, often passing at 80mph..... I averaged 22mpg. I'm gonna say it was all due to the tires. Skinny and 40# lighter than 33x10.50R15 KO2s. The handling especially on gravel is way more confidence inspiring. The ride.... I no longer try to dodge breaks in the pavement.... and the rolling resistance is enough to catch me off guard at red lights, forcing a sudden brake application.
Anyone wanting a ride or economy boost? Get real skinny tires. The 7.50R16 is very close to the 235/85R16 which is way more common.
These were also $200 less than 33/10.50R15s... and they are rated to go 33% farther.
Next job, building 2" flares cuz the 4" flares look like pantaloons.
My TJR will soon be skinnier than an SE !