Fuel economy on 35's
#51
JK Junkie
When I put on my 35s, I reset tire size and that wasn't quite enough. As you said the speedo was right but it was sluggish. I have an auto. I ended up doing a transmission reset as well and that helped a lot. The way I understand it, the transmission adjusts over time for your driving habits. So my transmission was adjusted for my stock wheels. After the reset, it pepped up immediately and learned how I drove all over again and seemed to compensate for the larger wheels, as it is no longer as sluggish as it was before. Still not as peppy as stock off the line, but a lot better than it was.
#52
JK Enthusiast
2014....I get about 13 with 315/70 duratracs, 3.21 gears, 2.5 lift, 4 door, no superchip or tuning at all...so I realize my speedo is about 10% off, but still under 15 mpg does suck...would love suggestions to improve.
#53
JK Enthusiast
Re-gear should help! As in understand being under geared can be as inefficient as over gearing I have 4.10s and I get 16 to 17 on same set-up (same tires and 2.5 lift). I am probably going to 4.56 shortly ... I have a manual and want the ratios back to where they were with my rubi when it was stock. Look into 4.10 or 4.56s
#55
Thanks for the reply. I re-calibrated my tires and checked them at 70mph with gps and speedometer is right on every 10 mph to 80 mph. I don't understand tune and shift points. I think the motor is just underpowered and doesn't have enough torque to maintain cruise without shifting but you may be right.
GW
GW
#57
I don't even comment or respond to the MPG inquiries any longer. Maybe I just don't care about MPG. Maybe I'm just baffled by those who buy a solid axle, 4x4, box body on ladder frame with a build specific to off roading and yet they ponder the sh**ty fuel mileage. Must just be me..........
#58
I don't even comment or respond to the MPG inquiries any longer. Maybe I just don't care about MPG. Maybe I'm just baffled by those who buy a solid axle, 4x4, box body on ladder frame with a build specific to off roading and yet they ponder the sh**ty fuel mileage. Must just be me..........
#59
technically, yes. As for anything truly insightful to gain MPG? No. Really, what's to gain? 1-2 MPG? 3 at best? Simple math will shed light on the very fact that dropping $300-$1000 on CAI, exhaust and tuners would take years, often beyond the intended usage and life of the vehicle for an owner, to see his/her savings to even cancel out the "investment" of the parts applied to gain said MPG. why "investment"? Because very few automotive dollars are an investment. It's all losses. But you can't put a market price on fun.
#60
JK Super Freak
From 13 to 15 mpg over 125000 miles at $3.50 per saves about $4,500
From 15 to 17 mpg over that same 125000 miles nets about $3,500 in savings
I'm willing to bet there are one or two here that have put (or will put) 125,000 miles on their JK while they own it and will recover the cost and more if prices go higher than they were. At $1.75 per that is still $2,250 or $1,750
For me, if I drive 75 mph I get measured 16.5-16.9 and at 65 I get 18-19 measured (calculated by miles travelled and gallons consumed using Billy's not so excellent Excel) so I just decide what is more important getting there sooner or with a couple of extra $$ in my pocket. Now top off or on the trail my mpg is crap, but I don't care, it's where I choose to spend my money
It's a Jeep, MPG shouldn't even be part of the conversation
Edit: I used to get better mileage, but tires and a mild lift beat that down some
From 15 to 17 mpg over that same 125000 miles nets about $3,500 in savings
I'm willing to bet there are one or two here that have put (or will put) 125,000 miles on their JK while they own it and will recover the cost and more if prices go higher than they were. At $1.75 per that is still $2,250 or $1,750
For me, if I drive 75 mph I get measured 16.5-16.9 and at 65 I get 18-19 measured (calculated by miles travelled and gallons consumed using Billy's not so excellent Excel) so I just decide what is more important getting there sooner or with a couple of extra $$ in my pocket. Now top off or on the trail my mpg is crap, but I don't care, it's where I choose to spend my money
It's a Jeep, MPG shouldn't even be part of the conversation
Edit: I used to get better mileage, but tires and a mild lift beat that down some
Last edited by zstairlessone; 01-25-2015 at 07:55 AM.