Bigger Tires, Better MPG on 3.0?

[SCOverlander]

Driving new Jeep (stock) from dealership in Utah to California 29mpg
2.5” lift with 35” tires @ 32psi= 17 mpg around town and 18mpg highway only @ 75-80 mph.

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[Santana74]

Stock Sahara and getting 25-27mpg. 31mpg is the best trip I made. Surprisingly it was up and down hills, but I drove 45-60mph.

 

[TX_Ovrlnd]

The diesels are much more efficient than folks let on, but you have to stay off that skinny pedal. I have a Banks Pedal Monster and penchant for wanting to go fast. My MPGs aren’t horrible but I’m only seeing around low 20s, once I have another tank of fuel under the 37s I’ll check again but so far it doesn’t seem like it took much hit.

 

[JINO]

Just got mine, stock (except roof rack), was doing about 68-69 (nice) on the way home and average around 25 mpg.
I'm guessing that'll go down with 35s.

 

[Terpsmandan]

Stock Sahara and getting 25-27mpg. 31mpg is the best trip I made. Surprisingly it was up and down hills, but I drove 45-60mph.

We spend most of our fuel on getting it rolling and moving the air out of the way. When I am in the Adirondacks (no traffic lights and very few stop signs) I was getting around 28 mpg.

 

[Compression-Ignition]

Better? Not mine, but I think on average we only lost 2-3 mpg going to 37’s. I don’t think I’ve ever seen more than a touch under 26mpg Highway on 37’s. Having said that I never saw 30mpg on stock tires. Think we saw 28.xx once.

 

[Ratbert]

Better? Not mine, but I think on average we only lost 2-3 mpg going to 37’s. I don’t think I’ve ever seen more than a touch under 26mpg Highway on 37’s. Having said that I never saw 30mpg on stock tires. Think we saw 28.xx once.

Never under 26 mpg on the highway with 37s?

Hypermiling?

Don't drive 75 mph+?

No additional weight like a winch / wife?

Overinflated tires?

Only drive downhill?

 

[Compression-Ignition]

Never under 26 mpg on the highway with 37s?

Hypermiling?

Don't drive 75 mph+?

No additional weight like a winch / wife?

Overinflated tires?

Only drive downhill?

Just worded weirdly.

I've never seen MORE, than 25.86 mpg IIRC. It was easy to see 23ish mpg going 70 on 37's.

 

[MountainRigged]

I weigh 220. I have 23 RubiDiesel 2.5in MC lift+TieRod/DragLink/SS. Metal factory bumpers. No winch yet. 37in D-rated Mickey ATs. Usually ride solo or with a 100lb kid. W/Tazer for gears. Stock gear ratio. 3.73

Stock I got 24city 28/29 highway 70 at most with conservative driving, but not grandma, also letting off gas early and coasting, not riding my brakes at the last bit of a stop. People will pass, I don't mind. Typically right lanes, or middle. Easy on the acceleration. I try to roll between city lights instead of stop and go.

After 2.5 MC lift and 37in tires I get about 18-20 city and 24-26 highway @ 65/70. Occasional 75.

 

[Old Jeeper]

The biggest factor in modern Jeeps is wind resistance/drag. Bigger tires mean higher profile and usually wider. Gone are the days that Jeep owners cruised around at 50mph max as that's all a lifted tj could muster with big tires and the top off. Most of us drive freeway+ speeds and get poor fuel mileage. The faster you go and the taller your rig the worse it gets period. Whenever someone posts an absurdly high fuel economy and backs it up with the trip computer, their average speed is below 50mph. One guy even had an average speed of 35mph over a 1500 mile trip. I'll drive fast and buy gas if that's what it takes to get great fuel economy from a Jeep.

Today's Golden Hammer award goes to Zandcwhite, for NAILING it.

I have watched the bending of physics since the days of TJs. Taller/wider the = more MPG everytime. Want big numbers, go big, 40s+ & `13.50s wide and add in a 5/6 in lift and the mpg goes so high that gasoline starts to come out the filler neck. So when he fills up he only adds a couple of gallons every few months.

So I told him about a trick us old timers do. Leave your OEM 33s on the front and put those 40s+ on the rear and you are driving downhill all the time...can you say MPG!

 

[Tredsdert]

I'm with y'all on that one. I noticed a massive difference in drag when I removed my tailgate. Rolling around with the top off and the tailgate on, was acting like a giant parachute. The second I took that tailgate off, I felt a whole lot less wind resistance pulling the Jeep down. Also between the rear seats and the tailgate being gone a little less weight and a whole lot less wind resistance!

 

[Terpsmandan]

Hers on 35's and stock except for the lift is getting 21 on the highway. Mine on 37's with a GDE tune and otherwise stock except for the lift is getting 22-24.

 

[JL_Wildlife]

I know, typically the thought is that bigger tires means more strain on the engine and more contact on the road, also bigger tires are heavier, so typically it's thought that bigger tires mean lower MPG. I would be out to say this is true on most gasoline engines, namely because they are a little less beefy and powerful typically than a similar sized diesel engine.

What I'm wondering is, are the diesel engines with all of their beefiness negating those things that would otherwise be strains on the engine, lowering miles per gallon, and just moving right past them unaffected. Without all of the outside factors, weight, resistance, strain on the engine and other parts, and in a perfect environment, bigger tires would mean better miles per gallon.

All of the people I see talking about their 3.0 EcoDiesels, the ones who are saying they're getting near 30mpg, all seem to have 37-in tires. I know from watching @Casey250 that the Eco-Diesels have no issues running 37s without re-gearing. I believe all he had to do was put in a taser JL and update the tire size on the dash, so that the speedometer matched.

I currently am getting an average of 23 mpg on 32-in tires. I'm curious to know what everyone else with the EcoDiesel is getting for their average miles per gallon, and also what their current tire size is?

I'm wondering if there might be correlation here, bigger tires on the EcoDiesel might mean better miles per gallon, versus other vehicles where bigger tires means less miles per gallon.

If you would, EcoDiesel owners, please list your average MPG and current tire size. Thanks and looking forward to everyone's answers.

I did a 3.5” Teraflex RT3 lift, 38” Trail Grapplers and 4.88 gears, I now get 15.5mpg. Love it :D

 

[Ratbert]

I did a 3.5” Teraflex RT3 lift, 38” Trail Grapplers and 4.88 gears, I now get 15.5mpg. Love it :D

That's pretty damn low for a diesel.

Is it well over 6k pounds? Or maybe you haven't adjusted your computer for the tires?

 

[JL_Wildlife]

That's pretty damn low for a diesel.

Is it well over 6k pounds? Or maybe you haven't adjusted your computer for the tires?

You know what, you are correct my friend. I have not adjusted the computer. So that MPG I would assume is not accurate. Final step in the process. Will be nice to see accurate MPG and hopefully it’s better than 15.5 lol

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