Fuel Mileage

[david_lee]

with those tires, when your speedo reads 65, you are actually going 70.42 which means that in an hour of driving at 65 you are going a full 5.42 miles further than your tripmeter or odometer reads. so, when you go to do your next calculation for fuel mileage you need to multiply your odo or trip reading by 1.0834 to get your actual distance traveled. its not all that difficult and will give you a better baseline.

 

[Danoflapper]

Filled up the front tank - 16 gallons exactly Let's see how I do, keeping the hubs unlocked crusing 55 @ 1500 RPM & I won't let it rev over 1500 in this tank.

 

[Chevyboy_0]

man your lucky to see double digits, my chevelle wont even go past 9 if im nice to her i havent had a chance to drive my truck enough to figure out the mileger but with the setup i have hopefully i should be lookin at 15 or so with 245/60/16(i think) t-19 and 3.55s with 2wd

 

[Chevyboy_0]

man your lucky to see double digits, my chevelle wont even go past 9 if im nice to her i havent had a chance to drive my truck enough to figure out the mileger but with the setup i have hopefully i should be lookin at 15 or so with 245/60/16(i think) t-19 and 3.55s with 2wd

 

[Goofyexponent]

I'm going to get my fuel system examined by a diesel repair shop just to make sure everything is right. new tires are out of the question right now, and I'm trying not to assassinate my wallet and buy the GV from the marketplace, even though i could use it so much. I have little repairs and all kinds of financial wreckage thats in my way.

Don't rule out tire size just yet my friend. I just punched in your tire size of 215 85 16 whish is ONLY .25% taller than my 245 75 16's. I got 23 MPG imperial, or 19 MPG American. I am running an F250 4x4 ext. cab. which had a PILE of steel in the bed. I know the rolling resistance of a dually is more than a SRW truck, but 12.4 MPG...?? That is a difference of about 6.4 miles per gallon. Pretty steep.

with those tires, when your speedo reads 65, you are actually going 70.42 which means that in an hour of driving at 65 you are going a full 5.42 miles further than your tripmeter or odometer reads. so, when you go to do your next calculation for fuel mileage you need to multiply your odo or trip reading by 1.0834 to get your actual distance traveled. its not all that difficult and will give you a better baseline.

ACTUALLY...the spedometer is off by 4.23% for the 215's so when he is at 62.6 he is doing 60 MPH...so we would need to multiply by 1.043

My tires are off by 3.98% so I need to multiply my miles by 1.04 exactly. when I am doing 62.04, i am actually doing 60 MPH.

I started out with 229 miles / 12.15 gallons of fuel = 18.8 MPG as a baseline!

So with this said....

370 kilometers = 229 miles

(370/1.61= 229)

229 miles x 1.04 speedo error=238.16 miles actually travelled based on the tire size difference in my truck.

I burnt 46 liters of diesel

46/3.78 = 12.15 gallons

So that means that...

238 miles / 12.15 gallons = 19.58 MPG, or 23.5 MPG as an actual figure.

I only gained about .5 MPG imperial.....and ssnce his tire size is a mere .25% TALLER than my 245's I seriously doubt that his fuel problem is tire size related.

Sorry if I came off as a jerk, I didn't mean to, but that is hard evidence!! lol

 

[Danoflapper]

man your lucky to see double digits, my chevelle wont even go past 9 if im nice to her i havent had a chance to drive my truck enough to figure out the mileger but with the setup i have hopefully i should be lookin at 15 or so with 245/60/16(i think) t-19 and 3.55s with 2wd

I'll trade ya straight up!

You're 9MPG has a lot more fun per gallon than my 12MPG does.

 

[Chevyboy_0]

I'll trade ya straight up!

You're 9MPG has a lot more Fun per gallon than my 12MPG does

haha true, but shipping from CA to MI would kill us both, and shes my first car and i dont plan on getting rid of her anytime soon

 

[david_lee]

Don't rule out tire size just yet my friend. I just punched in your tire size of 215 85 16 whish is ONLY .25% taller than my 245 75 16's. I got 23 MPG imperial, or 19 MPG American. I am running an F250 4x4 ext. cab. which had a PILE of steel in the bed. I know the rolling resistance of a dually is more than a SRW truck, but 12.4 MPG...?? That is a difference of about 6.4 miles per gallon. Pretty steep.



ACTUALLY...the spedometer is off by 4.23% for the 215's so when he is at 62.6 he is doing 60 MPH...so we would need to multiply by 1.043

My tires are off by 3.98% so I need to multiply my miles by 1.04 exactly. when I am doing 62.04, i am actually doing 60 MPH.

I started out with 229 miles / 12.15 gallons of fuel = 18.8 MPG as a baseline!

So with this said....

370 kilometers = 229 miles

(370/1.61= 229)

229 miles x 1.04 speedo error=238.16 miles actually travelled based on the tire size difference in my truck.

I burnt 46 liters of diesel

46/3.78 = 12.15 gallons

So that means that...

238 miles / 12.15 gallons = 19.58 MPG, or 23.5 MPG as an actual figure.

I only gained about .5 MPG imperial.....and ssnce his tire size is a mere .25% TALLER than my 245's I seriously doubt that his fuel problem is tire size related.

Sorry if I came off as a jerk, I didn't mean to, but that is hard evidence!! lol

by my calculation his tires should be ~30.39" tall and yours should be ~30.47" tall with the OEM tire size of my truck being 235/85/16 at 31.73" tall.
these are the correct numbers. what i stated earlier is right using the suggested tire size on the inside of my door. maybe your truck came with smaller tires.

 

[Goofyexponent]

What you are saying about the factory tires being taller than ours is right.

My point is that if smaller tires are causing bad milage, than mine should be about the same as Danoflapper's

By what 1010tires.com is telling me, I came up with the same tire diameters as you. The 215 tire is only .25% smaller than mine is, while the 235 is 3.98% taller than mine.

I ran the 235/85R16 which is what is recomended on the truck's door tag, which you said and is right, but I never noticed a huge difference in milage when I changed to the 254's (which are at about the same height as a 215).

The point I tried to make, amd I typed it fast and maybe I got it off wrong, was that the smaller tires shouldn't affect the milage that much. But you are right in that he SHOULD have 235's on there. I wasn't trying to make you look bad or wrong, and I am sorry if that's how it came out.

With the math I did, it only changed .5 MPG.

There is something wrong with that engine...or his right foot lol

 

[dslbroncotom]

Im gettin between 13-15 in my bronco, 7.3 idi, zf5, d70hd 4.10, and 35.5s. Also have the IP turned up 1.5 flats

 

[Revelstoke]

I've never gotten good mileage when I'm towing. I'd ask those guys who say they got better if they were towing. I've heard of the Cummins doing that, but that is all.

 

[Csgod0]

I think my problem is worn/bad injectors. I can hear 1 or 2 beginning to tick. It took lots of listening and playing with my fuel and its various additives while waiting for the warm weather to come to this conclusion. I am going to replace my return lines, injectors, o rings, pump timing, and increase pump flaps to see if I can either increase mileage, or at least get some more ponies.

 

[Danoflapper]

I got 15.8 two tanks a go and 16.4 on the next tank. Babying it paid off pretty good. I'm pretty content with that for now. I do miss lots of turbo noise though.

 

[93cc7.3]

at the pump right now and just got 17.5 city driving like a wild man hitting gov alot either my speedo is off or the additives e fan and new return lines and the such made a diffrence and i run 215 85 16 tires all six of them

 

[crashnzuk]

I finally got a number out of my dad from his trip home. He got 12 mpg on his last fill. He was slightly put off by his first tank so he didn't check until his last tank when he got home. This was towing a 23', 4500# bumper pull travel trailer between Twin Falls ID and Aberdeen ID (100 miles + or -). He was no doubt going 70 mph as he seems to find it creeps up on him while he's sight seeing. This is considerably better than the first tank of the trip where he ran one tank dry in about 120 miles going over the Sierra Nevadas. If he can keep his speed reasonable, I would be happy with 12ish while towing. We'll see how he does, he's leaving on a 7 week trip to New England and back around April 1st.
Travis..