8 Mpg.

Just bought the truck a month ago. Getting just under 8 miles per gallon. It's lifted, 37x12.5x20 tires, 5.7 lt. V8. Is that about what's expected?

 

Sounds probably about right with that size tires and wheels, and probably not regeared? They be big and heavy.

 

Yup - Lift = 2-3 mpgs, larger tires = 2-3 mpgs, heavier bumpers = 1 mpg; it all adds up (or down) fast....

 

Where are you getting your numbers? Dash read-out or are you calculating? If the latter, are you taking into consideration the odometer error due to the larger tires?

 

Is the former doing the same?

 

No, and I didn’t mean to imply that it was.

 

So stock tires are about 629 rev / mile, and OP’s big boots are about 545 rev / mile, for approximately 15% more miles than the odometer reads, unless it has somehow been corrected.

So a solid 9.IDGAF mpg instead of 8.

 

^^^^^^^^^ THIS ^^^^^^^^^

I have 35s and my truck shows that it's getting 8 MPG also. Need to figure for the change in tire size. It's normal.

 

Plus if OP hasn't done anything for speedo correction the truck is going way faster than indicated, and we all know how much these trucks guzzle at speed. If OP sets the cruise at 75 he's really going about 87

Even my factory skinnies won't get 12 mpg at that speed

 

I have 34s avg 13.8 ...

 

Normal, big v8 truck running 37s with stock gears = 8-12 MPG.

You are probably getting a bit better. Truck MPG gauge is based off stock 32inch tires. You need to add the % difference in tire size to the miles you traveled. Then divide that by the number of gallons you pump in at fillup- that will be your actual MPG. 37s are 15% bigger than 32s, so if your truck says you traveled 200 miles, because you have 37s, you have actually traveled 230 miles. Use that 230 for your MPG calculation.

 

6 inch lift on 35s and I get 13 to 13.5 in mixed driving, babying it. Highway almost gets 15.

 

I’ll bet that if you spent a day at the drag strip you could knock that number down to 3!

 

Do the speedo calibrators affect the odometer calculation? I'd assume so...

 

Thank you for all of the responses. I am aware of the speed difference. I figure close to 18 -20 mph at speeds of 65 mph. I appreciate the posting showing the lift, tire size and front bumper mpg loss.

 

Use 10% while driving for simple mental conversion. 65MPH is about 72MPH, not 83MPH. I have the same setup on stock gears and average 11.5MPG. If it's primarily interstate driving, using fifth gear (basically copying final ratio of 5.29s) I get 13.5MPG. Sounds like you could drive a bit lighter if you wanted a bit more efficiency. My numbers fall in line with posts by other guys, too.

@texasrho83, yeah, modified CAN messages affect the odometer. That was the primary reason I implemented my system.

 

10-11mpg is average for 37s.

 

Pretty much right at 14 with 34’s and 5.29’s. Speedo is almost perfectly corrected. She’s just a tad off. All stock, my drive to work was 18.8 miles. It’s now 18.9…

 

Keep in mind the added speed also means more miles than the odometer reads. If you bought it used with say 100K miles, you could be off by several oil changes worth.

Rule of thumb; don't buy lifted, especially when the seller looks like a deer in headlights when you ask about speedo/odometer correction.