Gas mileage

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Jacob Metz

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idk if this is the right forum. But I wanted to see what everyone’s getting for mileage on their nbs. I’m currently on 35s and getting 8mpg idk what to do to have it go up

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Scottydoggs

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welcome to the world of "you run large wheels" they are cool, but kill mpg.

i had a 03 2500 hd pick up, came with 4.10 gears, i then added 33's, i went from like 450 ish a tank to 300 ish. i had a huge tank too, 34 gal, so i was in the 8-10 range.

for work i had to do fuel and mileage reports with your mpg avg done via your miles and gallons used. was always right around 10 mpg. and i did a lot of hwy. about 200 miles a day.
 

SnowDrifter

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A re gear might help, but you're still fighting physics here. These hoes are large vehicles as is. Both weight and volumetric size. Putting 35s on the thing makes it that much worse. You're basically forcing a barn with 4 wheels through the air.

'Tis the nature of the beast.
 

Martinjmpr

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I'm resisting the impulse to say "sell it and buy a Prius" but I actually do get it - when you have to pay for gas, it makes sense to get the best MPG you can.

To answer your question realistically, we need more information. Year? 2wd or 4wd? Miles? Gear Ratio? What other mods do you have?

What kind of driving are you doing? Stop-and-go city or suburb driving? Long highway miles? With a vehicle as heavy as these, stop-and-go will kill your MPG no matter what else you do.

Also how are you calculating your mileage? If you're going by the DIC readout consider that unless you have re-calibrated your speedo and odo that is going to give you an inaccurate rating. Also, the DIC is not really a good way to determine actual MPG anyway, to do that you need to hand calculate.

If you want to accurately measure MPG the first thing you have to do is figure a way to calculate your actual miles driven.

Here's how I did it on my Suburban after I put bigger tires (33's) on: Get a GPS mounted. Then go to the trip meter on the GPS. Set the GPS trip meter to 0, and set the truck trip meter to 0 also.

Drive at least 100 miles with the GPS on (more is better.) Make sure the GPS is always recording mileage driven. After at least 100 miles compare the two. If you have oversized tires, likely the GPS will show more miles than the truck odometer (because your bigger wheels have a greater circumference the odometer only knows how many revolutions your driveshaft is turning, not how many miles you are actually going.)

Compare the two numbers. Let's say the truck odometer shows 350 miles and the GPS shows 360.3. 360.3 / 350 = 1.03. That means that from now on, you have to multiply the truck's odometer reading by 1.03 in order to get an accurate distance.

Set the truck odometer to 0 when you fill the tank. Drive as normal. When it's time to refuel, fill the truck up and write down the number of gallons it took to fill the truck. Multiply the miles x 1.03 (or whatever your multiplier is) to get actual miles driven and divide by gallons used. That is your ACTUAL mileage (as opposed to what's on the DIC.)
 

Martinjmpr

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2001 Tahoe 5.3 4x4 factory gears

Do you know what ratio? It should be on the RPO code sticker on the dash. Also you can create an account with GM and they will send you a build sheet that shows all the options your vehicle has based on the VIN.

Reason I ask is that if you have low gears already (like 3.42) then having big tires lowers the ratio even further and that can cause your engine to be operating at either excessively low or high RPMs. Also you didn't say what kind of driving you're doing. Stop and go driving is an absolute killer in these vehicles because they weigh over 5000lbs and every time you stop, you have to get all that mass moving again, which requires a lot of engine power.

If the issue is gear ratios, you're going to have to decide whether spending $1000+ is a good investment, because that's about how much new gears will cost (you need two sets, obviously, since you have a 4x4.) You can buy a lot of gas with $1000.
 

castine917

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idk if this is the right forum. But I wanted to see what everyone’s getting for mileage on their nbs. I’m currently on 35s and getting 8mpg idk what to do to have it go up

View attachment 214161
Our 05 5.3 tahoe 4x4 would get @15 mpg. It had 35s, 4.56 gears, an air intake, exhaust used premium fuel and a 'programmer'. Driving was mainly 45 mph city areas with light traffic. Highway time would reduce mpg.

Years before that we had a 97 f150 5.4, that would get 14. 4x4, 38s, 4.56 gears, air intake, exhaust, used premium fuel and programmer. That one spent more time on 55 mph country roads. On this one highway would help mpg.

With factory gears you are probably having to floor it to accelerate since it would take forever to get moving. How is your tune/tuneup/fuel leaks? Do you have bad bearings or brakes dragging? Are you trying to do 90 on the highway? Any or all of those will kill mpg.

As martinjmpr mentioned, gears cost as do my other modded items. The difference between your 8 mpg and my 15 will take around 35,000 miles at $2 per gallon to pay for those parts.
 

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