5.0L mileage with 20's and 3.31s
12-09-2012, 08:41 PM
#2
No but I drive for fuel economy. E.g. Don't drive up to red light but coast in, easy on the gas at green and can get 50k miles plus out of OEM brakes and tires. How about you?
I also only buy gas at top tier stations and live in relatively flat Texas. So many variables, even the specific city driving dynamics, as no two cities have the same speed limits, distances between lights, amount of lights, delay between lights etc..
Without more information 13 mpg is perfectly reasonable. Why don't you post more information and get an informed decision instead of turning this into yet another pissing match over who can post the best mileage, like many other threads that you can search for and read already?
I also only buy gas at top tier stations and live in relatively flat Texas. So many variables, even the specific city driving dynamics, as no two cities have the same speed limits, distances between lights, amount of lights, delay between lights etc..
Without more information 13 mpg is perfectly reasonable. Why don't you post more information and get an informed decision instead of turning this into yet another pissing match over who can post the best mileage, like many other threads that you can search for and read already?
Last edited by kydsid; 12-09-2012 at 08:45 PM.
12-09-2012, 09:51 PM
#3
Intake tune exhaust.... Soon to be long tubes 85mm throttle body... But I live in Houston.. And drive city 85% of the time and have the 3.31 rear end with the 20" wheels ... It came with 18" wheels... So what I'm asking is if others are getting crappy mileage from the swap of bigger tires/ wheels with the highway gear... Yes I have read sh*^ tons of people saying they get 18-20 ...
12-09-2012, 09:52 PM
#4
I have 265/50/20 with 3.55 axle. My truck is a RCSB 2wd and says I am getting 18.6 avg mpg since putting the tires on at 2200 miles. No real change after I switched from the stock 235/75/17's. 13 is pretty low. My Lightning got between 14/15 consistently.
12-09-2012, 10:53 PM
#6
Intake tune exhaust.... Soon to be long tubes 85mm throttle body... But I live in Houston.. And drive city 85% of the time and have the 3.31 rear end with the 20" wheels ... It came with 18" wheels... So what I'm asking is if others are getting crappy mileage from the swap of bigger tires/ wheels with the highway gear... Yes I have read sh*^ tons of people saying they get 18-20 ...
Lets look at one simple variable, the wheels. Stock 20's? or aftermarket. Wheels weigh different weights. More wheel and tire weight is a very easy way to kill mileage. You could have kept 18s, but gone with heavier ones and lowered your mileage.
There is no way with everything on your truck to compare it to a stock truck and see if there is a problem. You need to eliminate a single variable at a time and test.
All that said I am in Houston and I will say three things that are opinion. People saying 18-20 in the city are full of it and/or the test range, data input to achieve that was so limited it is of no meaning. Two I can drive my truck in such a way to get 13 to 15 mpg and it is stock. So I don't think you have a problem.
Back to the facts. More info would be needed from you to figure anything out. Even then it would be dificult to determine. The bigger question is why do you and so many others think there are issues that mpg are showing? Do you have rough idle, slipping gears or any other indication of mechanical issues. That in addition to so many other variables would put you in a better direction of thinking other than to think the 20s are immediately the problem.
Heck start simple. Take the truck as is and run at 60mph out and back to Beaumont or the like. Use cruise. Fill the tank before and after and calculate by hand, because surprise surprise another variable is mpg estimations by the truck can be wrong.
Good luck
12-10-2012, 06:12 AM
#7
I am not saying there is a problem, I was just asking if what I'm getting was about par with what others get... Also at 65 mph my mileage is not very good I h e to go up to 72 to see the best mileage, I believe it has to do with the tire height and gear combo... Which was what I was inquiring about... I understand rotational mass has something to do with it so does driving habits and so on ... I was just asking about 3.31 gears and 20's to chime in on 5.0L
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12-10-2012, 07:19 AM
#8
If you are getting better mileage at a higher speed then it isn't your tires and rear ratio. I'd be looking at the tune and other modifications made to the engine. Without a doubt I get better mileage the longer I cruise at a slower speed.
12-10-2012, 10:01 PM
#9
Senior Member
With a 3.31 rear and 20 inch tires you are not far from average for the "city average" not the overall average. As others say, many variables come into play, speed limit, traffic, amount of traffic lights, idle time at traffic lights (you can be sitting 3 to 4 minutes at busy intersections), your driving habits, slow start vs fast start, even the gas at certain times of the year (lower mileage with winter blend gas).
The truck works harder to move the weight from a dead stop with your configuration using more fuel to get the mass going. If you had a 3.73 rear you most likely would see an improvement in your city miles.
3.31 with 20's will shine on the freeway and give you the most mpg's, a 3.73 rear will give you less.
General rule of thumb
.........city mpg / mid speed mpg /freeway speed mpg
3.31 low..............average.......................goo d
3.55 average........average......................averag e
3.73 good........... average.......................low
The truck works harder to move the weight from a dead stop with your configuration using more fuel to get the mass going. If you had a 3.73 rear you most likely would see an improvement in your city miles.
3.31 with 20's will shine on the freeway and give you the most mpg's, a 3.73 rear will give you less.
General rule of thumb
.........city mpg / mid speed mpg /freeway speed mpg
3.31 low..............average.......................goo d
3.55 average........average......................averag e
3.73 good........... average.......................low
Last edited by Alcoloco; 12-10-2012 at 10:11 PM. Reason: Spacing
