Thanks for the advice. The Jeep has a horrible kidney shaking ride.
I have a 6 speed manual powered by the 4.0L inline six. My favorite gas saving mod so far has been removing the front drive shaft. I know a lot of people swear it does not spin while driving but driving the Jeep @ 60Mph without the front driveshaft requires a lot less "gas pedal".
I lost all respect for my image as soon as car dealers offered me $5,500 for my 2005 Jeep TJ I-6. So much for dumping my Jeep to get a Prius!
I know the older Jeeps had leaf springs. Great for off road, not so great for ride quality. Does your 05 have leaf or coil springs? Your mileage can improve, but be aware. You may not get a huge payback. Take my truck for example. A 10% gain in economy translates to a little more than 1 MPG. I've put a lot of work into my truck and driving style and total I've only gained 2 or 3 MPG.
You posted a 215/85R16. Based on my 3,000 pound car on 195/65R15 tires, which rides and handles great at 50psi, I think you'll probably not want to exceed 50 in the Jeep. I'm surprised that 95CHERJUST is able to run 50psi in his 3,000 pound jeep on those big tires.
All that considered, you might look for 51psi-rated P-metrics instead of the LT-series tires that give you higher pressure. P-metrics should have lower rolling resistance, all other things (pressure, tread pattern, exact size) being equal, due to the more pliable thinner carcass.
Yeah, That's why I mentioned earlier that maybe he should look into D's. I think the E's will be far to harsh. D's will allow higher tire pressures than normal without being too rough. He's already got a short wheelbase probably riding on at least 2 leaf springs. Don't make it worse by pumping up tires to 70 or 80 PSI. The D's should operate in the pressure ranges where at the tire's max pressure you're probably hitting the minimum tolerable ride quality anyway.
My Jeep TJ has coil springs. I ordered the rims and will start shopping the local tire stores since they can sell me tires cheaper as a result of no shipping fees. I agree 50+ PSI is going to make my ride rougher and will have thicker walls due to the increase PSI.