213jeep

I just ordered my teraflex 2.5 bb planning to run it with 35's (325 65 18) kind if worried about gas mileage because it's my daily driver and I drive 45 miles each way everyday will a see significant mpg change ?

213jeep

That's 325 65 18

Mark Doiron

The immediate answer is, yes. You'll see a drop in gas mileage. Whether it's significant or not depends on how sensitive you are to gas mileage. I'd guess 2-3 MPG drop--but that is just a guess, really, based on the seven years I've been gradually modding my Jeep and shifting its gas mileage from the stock 18-20 (highway) to 14-15. You can ask folks on JKF what mileage they're seeing, but their answers will be all over the map. And most of them will not (unless you ask directly) share how they arrived at their gas mileage figure:

• Computer or hand calculated?
• Speedometer calibrated?
• 100% gas or ethanol-laced?
• Driving style?
• Driving, road and weather conditions?
• Significant mods?
• Etc.

You'll also have some folks who claim to have actually increased gas mileage when the lifted their Jeeps and put larger tires on. They should be working for the automotive companies.

Bottom line:

• If gas mileage worries you, you're on the wrong path in the wrong vehicle.
• If you want the "best possible" answers, you'll need to share more info: Current gears, engine, etc.

Also, expect some grief over those 18" wheels. And those who defend your choice of them.

BlackRockBurner

Another mpg thread...3.8 or 3.6 Pentastar? What gear ratio do you have? What's your elevation? AllTerrain or MudTerrain? How heavy is your right foot? With the 3.8 expect minus ~5 or so mpg. 3.6 is better. Aerodynamic drag and rolling resistance along with driving habits are key to improving mpg. Thousand dollar re-gearing may give back a few mpg. If mpg is really important then don't do anything to the jeep, absolutely nothing. Well go with smaller less than 30" low rolling resistance street tires and smaller lighter wheels to see an improvement over complete stock.

213jeep

I have a 20012 4 door jk penstar wheels are all terrain not mt I know if your worried about gas mileage u should get a Jeep but times are tuff and there's no way I'm getting rid of my baby just asking !

BlackRockBurner

Mpg is just a question that can't get a specific answer. Get two identical Cars, not even Jeeps, off the assembly line and give them to two drivers in two different states and you'll get two different numbers in mpg. Now throw in modifications to jeeps with no two being identical and there is no baseline to compare to.
Your rolling resistance is solved with AT, so it's all about aero drag, weight and throttle control now. Keep it under 65; run with minimal weight and slow smooth launches with minimal braking to get the best mpg.

Mark Doiron

I do a lot of trips between Oklahoma City and San Diego. This ^^^^ will give me 2-3 MPG as opposed to driving 75 MPH.

Battlefrog21

Lately with traffic here in San Diego, I can't get the jeep over 65 anyways.

I average 15.4