Just went from lowered to lifted... The effects on ride and mileage.

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augiedoggy

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So I figured Id share my recent experience for better or worse with a 2015 tradesman ecodiesel crew with 6.4 bed 4x4 I bought a few months back.

First off, When I bought the truck the small used car dealership said nothing about it being deleted, tuned or lowered... I discovered it had a lot of mods along the way. One thing which looked odd to me was that it had a 2wd stance with 31.5" nitto all terrains on it which seemed odd on such a long truck. it also rode pretty rough. the tires were 4 ply G2s and the truck got amazing fuel mileage. I averaged 24mpg around the city and 34mpg on a 2 hr mainly highway round trip to my camp and back.

After going back and forth and looking more closely at what I had I discovered someone had put adjustable lowering struts on the front to drop it 2 inched and it had a 4" drop kit in the rear making both the front and rear fenders sit about 34.5" off the ground.

I decided I wanted to change the suspension as I didnt care for the rough ride and one of the red airlift bags had a large rupture in the rear.

So I installed bilstein 5100 struts and shocks using the original springs in the front but superlift 2" lift variable springs in the rear with new air bags in the springs. I also had to replace the rear link bars and remove a relocation bracket.

I then purchased some used 34" AT tires (10 ply) to see how the change effected mileage and such. I reprogrammed the tire size with alpha obd, had an alignment done. and the new tires are on 18" rims.

The truck looks completely different. while im NOT impressed with the 10 ply tires, the 5100 struts and shocks give a much better overall ride. The fuel mileage went dramatically down. I now get like 17mpg in the city and 23 on the highway. I have ordered some 4 or 6 ply nitto G2 34" tires which are only 51lbs each vs 69bls as my current tires are which I hope will help. I also hope the tire vibration/road feel will be smoother as it was with the 31" g2s im hoping the transmission will hold gear better without downshifting at it does now although I realize some of that is due to the taller tire changing my final gear ratio and load on drivetrain.

At the end of the day If I had to do it again I likely would have just looked for some better struts and shocks and more attractive larger diameter rims to make the lowered look work for me. I love the look of the 3-2" lifted truck which is actually like 5" higher in the front and 6-7" in the rear from where it was. But I am at the point after having multiple lifter offroad capable 4x4s where I care more about the creature comforts such as mileage and ride quality on road trips pulling my popup and such.... Sucks getting old.
 
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augiedoggy

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The taller you make a barn door, the more wind resistance it has. The weight of the barn door only matters at low speeds.
Yeah Ive read that before... We shall see I guess how true that statement is I guess. In this case the barn door is the same size... its just letting more wind under it which does create a bit more resistance. But they say the rake reduces wind resistance for better mpg as well (even though its making that barn door taller) and mine has been leveled both when lowered and almost level now with about an inch of rake. I have no doubt the truck being lowered before helped achieve the above average fuel mileage.

The thing is my MPG went down at ALL speeds... its even drastically lower at 30mph according to the computer, and the transmission behaves much differently due to the additional load from what I believe to be a mix of three things including wind resistance from more wind getting under the truck, tire weight and tire diameter which makes the 3.92 gears with 34" tires behave more like the 3.55 gear ratios with stock diameter tires. I'm not expecting to get all the mileage I had back, Just some of it would be nice and I believe the tires will make a big difference. a barn door doesnt have tires, and Ive read the rotating weight of a tire has multiple times the negative effect of that same weight if placed "in" the truck.
 
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crash68

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The taller you make a barn door, the more wind resistance it has. The weight of the barn door only matters at low speeds.
^^^ this
Going from 20 mpg towing an18' boat which weighs 3200 lbs, that will drop to around 16 mpg when I have the 24' enclosed car hauler which only weighs 3K lbs when empty. Even if the trailer is loaded up I'll only drop may 2 mpg.
 

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If ever a post needed pics it's this one. I'm dying for before and after shots.
 

HEMIMANN

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Your center of gravity is raised also, requiring slower turns and / or monster wide tires to counteract.
 
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augiedoggy

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Your center of gravity is raised also, requiring slower turns and / or monster wide tires to counteract.
Yeah makes sense but I havent really noticed this so much but the tires are a half inch wider I guess.. I dont really drive it like my stingray either.. it is a diesel truck... Dont get me wrong its no slouch even with the tires bogging it down.

Years ago I had a lifted wrangler with the 2.5 4cyl. I had the 5 speed stick and 31.5 4 ply kelly safari tires... I decided to put 32" bfg mud tires on it.... Well that change alone with no additional lift made it such a dog I couldnt use 5th gear on the highway anymore and hold highway speeds and my mileage went down the toilet since I was always over gassing it and it was always struggling. Then I had the 4.10 gears swapped with 4.56 gears. It was like a new jeep all over again. My gas mileage improved dramatically in all types of driving. And I was able to use 5th gear again. And this was with a tire diameter increase of 1/2" but a large weight difference.
 
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terrible

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Your mileage probably didn't change but some one didn't reset the computer with the previous tires. Or they did reset it and went the wrong direction giving you a false MPG.
 
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augiedoggy

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Your mileage probably didn't change but some one didn't reset the computer with the previous tires. Or they did reset it and went the wrong direction giving you a false MPG.
In what world would larger heavier tires with 6-7" of lift cause the MPG to improve though?

I have corrected the computer settings and reset all mileage counters. The computer tire size has been reprogrammed with alpha OBD and the entire dash cluster was upgraded to the 7 lcd display later. All this and of course the more frequent trips to the diesel pump, tells me the computer results make sense. when I bought the truck I got well over 600 miles to a tank with mixed driving. (closer to 700 actually).

I'm still waiting on the long backordered lighter tires to arrive that I ordered from Jegs (and paid for) months ago.
 

StickyLifter

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Tire and wheel weight and overall diameter can have a massive effect on fuel mileage and vehicle performance because the total mass is not only unsprung but also rotating weight. That rotating part is a big deal, and if you want to visualize it, think of how hard it would be to stop a yo yo if it weighed 200lbs and was spinning on a 10ft long chain.

The OP is correct.

When you jack your truck up and put on huge mud boggers and heavy bro wheels your mpgs go to crap and so does all other aspects of vehicle performance until you drive offroad. There is no free lunch and you can't fight physics because gravity is kinda a constant deal throughout the universe.
 

HEMIMANN

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Tire and wheel weight and overall diameter can have a massive effect on fuel mileage and vehicle performance because the total mass is not only unsprung but also rotating weight. That rotating part is a big deal, and if you want to visualize it, think of how hard it would be to stop a yo yo if it weighed 200lbs and was spinning on a 10ft long chain.

The OP is correct.

When you jack your truck up and put on huge mud boggers and heavy bro wheels your mpgs go to crap and so does all other aspects of vehicle performance until you drive offroad. There is no free lunch and you can't fight physics because gravity is kinda a constant deal throughout the universe.

Who knew keeping up the dude life costs so much? *sarcasm*
 

Wild one

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Yeah Ive read that before... We shall see I guess how true that statement is I guess. In this case the barn door is the same size... its just letting more wind under it which does create a bit more resistance. But they say the rake reduces wind resistance for better mpg as well (even though its making that barn door taller) and mine has been leveled both when lowered and almost level now with about an inch of rake. I have no doubt the truck being lowered before helped achieve the above average fuel mileage.

The thing is my MPG went down at ALL speeds... its even drastically lower at 30mph according to the computer, and the transmission behaves much differently due to the additional load from what I believe to be a mix of three things including wind resistance from more wind getting under the truck, tire weight and tire diameter which makes the 3.92 gears with 34" tires behave more like the 3.55 gear ratios with stock diameter tires. I'm not expecting to get all the mileage I had back, Just some of it would be nice and I believe the tires will make a big difference. a barn door doesnt have tires, and Ive read the rotating weight of a tire has multiple times the negative effect of that same weight if placed "in" the truck.
The old school rule is every pound of rotating weight is equilavent to 4 pounds of static weight
 

DILLIGAF

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requiring slower turns and / or monster wide tires to counteract.

No true I still drive mine like I stole it. But I used top of the line components.

It actually handles better then a stocker with all the subpar parts and soft ass bushings it has.

and my 37s feels like im driving on a cloud.
 
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augiedoggy

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So I have had my new replacement 4 ply 34" nitto g2s now for a couple months... the 4 ply tires increased my average mpg 2 mpg to 17-18mpg with mainly city driving over the 10 ply tires. so there you go, dropping 20lbs of weight per tire did help. I havent had any serious high miles since the new tires have been installed but im expecting around 26-27mpg.



The thing is, I dont have one of those kids rides with the tires sticking out, A friend has a new stock f150 and my truck parked next to it has about the same ground clearance as it and the tires do not look oversized at all. If my truck hadnt been lowered when I bought it which I feel makes as much sense for a 4x4 as having those tires that stick out the sides spraying water mud and stones all over everything, I wouldnt have even lifted it the 2" over stock. that said the 33" tires I test fitted looked too small at that point
 
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augiedoggy

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No true I still drive mine like I stole it. But I used top of the line components.

It actually handles better then a stocker with all the subpar parts and soft ass bushings it has.

and my 37s feels like im driving on a cloud.
Well you must have 4.56 or 4.88 gears installed for it to not be very sluggish. otherwise, from experience on multiple lifted vehicles when I was younger including 2 before and after 4.56 gears, they became very slow and sluggish until the gears were replaced, which more or less returns the final gear ratios back to stock. and that was only 32 and 35" tires in those cases. I actually sold my old lifted ram because it just wasnt practical or fun on long trips, especially towing. They were fun when I was younger and actually did some offroading but not so much anymore.
 
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augiedoggy

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Its literally posted in my sig line
Great, I dont read everyones biographies on forums. Anyway I didnt need to read it did I since I already knew it would be a dog otherwise. :)
So your truck with 37" tires and 4.56 gears is about the equivalent of a stock truck with 3.55 gears as far as final gear ratio but with the added tire weight... I actually have about the same final gear ratio now with my 3.92 gears and 34s and I can confidently say my truck it more sluggish than it was with the 31" tires so the wind resistence and tire weight has to be making the difference.
The transmission shifts completely differently as well I have to overshoot and let off the gas to get it to upshift at times. it kinda reminds me of driving my old buick now... great smooth cloud like ride but its not going anywhere as quick as before. Granted my deleted and tuned truck is only giving me about 300hp but the 500lbs of torque should be plenty for this setup.
 
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