Decrease in gas mileage with leveling kit

[bbass3]

I just installed a 2.5 rough country leveling kit on my 08 silverado. I was getting around 320-350 miles per tank down to 250-270 while leaving stock wheels and tires on it! Any reason this could happen? I've read a lot of forums that say a leveling kit shouldn't decrease gas mileage with stock wheels and tires. Thanks and any help would be appreciated!

[oldmann]

They were absolutely wrong. Increasing the profile of a vehicle totally changes the aerodynamics. Also, who knows what condition the alignment is in now.

[jhm]

They were absolutely wrong. Increasing the profile of a vehicle totally changes the aerodynamics. Also, who knows what condition the alignment is in now.

Bingo!

[Doug_Scott]

They were absolutely wrong. Increasing the profile of a vehicle totally changes the aerodynamics. Also, who knows what condition the alignment is in now.

The alignment may not even change, depending on how the truck was leveled. If it was leveled by lowering the rear, the only change to alignment would be to the caster reading, if the change was even readable.

Altering the front height may change camber and caster.

 

Not sure the angle of the truck would have much impact on mileage since all you are doing is taking a brick that is at a slight angle and therefore is presenting a larger frontal area and reducing the amount of frontal area by not showing the entire top of hood/roof/box to the air stream. By lowering front or raising rear, I would expect a minor increase in mileage, not worse.

 

The kid in me wants to say the mileage is worse because the truck in not running downhill anymore.

[TimmyG]

My 3in body lift and air dam remove cost me close to 2mpg

 

Sent from my SCH-I535 using Tapatalk

[bbass3]

It is a 2.5" front suspension lift and 2" rear blocks instead of factory 1" blocks. Also I had it aligned the day it was installed

[Doug_Scott]

My 3in body lift and air dam remove cost me close to 2mpg

 

Sent from my SCH-I535 using Tapatalk

 

I can see that happening, you made the front of your truck 3 inches higher, while also keeping the lower edge at stock height. Like taking a 4x8 sheet of plywood, and attaching a 3 inch strip across the full width.

[j13smiley]

even then he's talking about 50-100 (per tank) loss. no way a leveling kit kills mileage that much.

[sledge62]

I put taller tires on mine (55's up to 65's), a 2" Rough Country leveling kit....... I lost about 2-3 mpg... 2014 Silverado LTZ Z71 - 5.3L 3:42 gear

[Doug_Scott]

I put taller tires on mine (55's up to 65's), a 2" Rough Country leveling kit....... I lost about 2-3 mpg... 2014 Silverado LTZ Z71 - 5.3L 3:42 gear

 

How far off is the speedometer? Taller tire means slower speedometer reading, which also means lower number of miles traveled, according to odometer, which then means drop in mileage. If you also changed section width along with aspect ration going up, the overall diameter may not change between the two, so the only thing left is the total weight of wheel and tire, times 4 compared to stock. Increasing the unsprung weight has an impact as well.

[Doug_Scott]

even then he's talking about 50-100 mpg loss. no way a leveling kit kills mileage that much.

 

Truck only started out with about 20mpg, how can it lose even 50mpg? I realize it is a typo, but, I can't see where the typo is to help me with comprehending your posting.

[sledge62]

 

How far off is the speedometer? Taller tire means slower speedometer reading, which also means lower number of miles traveled, according to odometer, which then means drop in mileage. If you also changed section width along with aspect ration going up, the overall diameter may not change between the two, so the only thing left is the total weight of wheel and tire, times 4 compared to stock. Increasing the unsprung weight has an impact as well.

 

Best that I can tell, its about 1-2 mph off... so, you maybe be right... the total weight of the tires changed, the tires I put on are a 10 ply tire... so I am sure I added somewhere in the neighborhood of about 200 lbs when I changed the tires.

[Doug_Scott]

 

Best that I can tell, its about 1-2 mph off... so, you maybe be right... the total weight of the tires changed, the tires I put on are a 10 ply tire... so I am sure I added somewhere in the neighborhood of about 200 lbs when I changed the tires.

 

The amount a speedometer is out is generally in percentage and can be predicted fairly accurately if you have the overall diameter of old and new tires. I have a site that I use from time to time that will tell you how far off your speedometer will be off by at any speed you want. I will send the link via PM. Can't post links in the forums.

[Bob D]

I would estimate (from his original numbers) his mileage reduction to be about 2.6 mpg.

If exclusively highway miles, it seems in the realm of possibility.

[j13smiley]

 

Truck only started out with about 20mpg, how can it lose even 50mpg? I realize it is a typo, but, I can't see where the typo is to help me with comprehending your posting.

 

hehe - per tank ;)