15.94mpg with 35" tires.

Previously on this exact same (work) commute, the best I was seeing was 16.1mpg with the unlifted truck on bone stock tires.

I can live with the trade-off of 1 mpg for the bigger tires and 3" lift.

This is average driving like grandma would drive. Not hot-dogging it... but not crawling either.

 

Did you correct the speedo?

 

Nope... and I was wrong about the 16.1 previously. I dug around in my phone and found a pic.

Previous was 16.4 mpg and trip is exactly 25.4 miles.

Current shows 15.0 and 23.9 miles. (actual is 25.4)

Not sure how the Math works out on that.

 

What tires are you running? I’m only getting 13.0 MPG (hand calc) on 33”s

 

All bets are off on the computer after the bigger tires. You'll need to figure your MPG the old fashioned way by doing math.

The last two tanks through my truck (2018 crewmax on 35x12.5) were calculated at 13.7 and 13.6 MPG HIGHWAY.

 

OK... so here's what I came up with... and keep in mind... Math is not my strong point.

Assuming the truck computer calculates MPG based on fuel consumed over a specific distance.

23.9 miles traveled, divided by 1.5925 gallons of gas consumed = 15.00 mpg.

Fuel consumed is a constant... so if I plug in the ACTUAL distance traveled... it looks even better.

25.4 (actual) miles traveled, divided by the same amount of fuel consumed (1.5925 gallons) = 15.94 mpg.

Can anyone debunk or correct my fuzzy Math ?

 

I will start printing fuel receipts and keeping an eye on it the old fashioned way... but I like the trucks computer way better.

 

LT35x12.5-18 Nitto Terra Grapplers.

45psi front, 42psi rear.

 

LOL, yes your math is correct. Actual distance divided by gas in, nothing fancy about it.

For reference, since you went 25.4 miles actual vs 23.9 miles indicated, you can just multiply what the truck reads by 1.06x since that's how much bigger your tires apparently are vs stock.

 

23.9/25.4 = 0.94094488.

0.94094488x15=14.11 MPG.

 

Actual distance traveled (25.4) is further than the computer calculated (23.9) but fuel consumed remains the same... so I think that math is off. (in the wrong direction)

 

The commute is identical every day, driveway to driveway... and in all fairness... when I'm running late and hammer-down... I will only see 11-12mpg at the end of my commute.
So it pays to get out of bed on time.

 

Well opposite is 25.4/23.9 = 1.06276151. 1.06276151 x 15= 15.94.

Not unusual. I have 34x11.5 nittos and can get 16/17 on the highway.

 

That sounds about right... as I was getting 18.1 in bone stock trim. The 35's should put me squarely in that 16/17 territory. Maybe even better if I run the tires at the 80psi max.

 

Common core math?

 

Meanwhile, I'm getting 11mpg on 37's

 

I had considered 37's but settled on 35's because I didn't want the extra work involved with making them fit.

 

Nah... common sense Math.

 

I think the correction can be done in HP Tuners by adjusting the tire radius numbers... so when they finally support the 2020 trucks, I will dabble with it a bit.

 

No those are both wrong lol. You guys are killing me. You drove FURTHER in real life than the computer thinks (25.4mi real life, 23.9mi computer thinks) so obviously you got better mpg than the computer says because you went MORE miles than the computer thought. Your first attempt was correct, you got 15.9mpg. Your computer mpg multiplied by 1.06 (tire correction factor) gives real life mpg.

 

Yeah I think we both landed at the same conclusion about the same time.

15.94 seems pretty accurate, considering the info we have to work with.

 

I haven’t had algebra in 20 years. I think my formula was backwards.

x/y = a/b ?

 

I graduated HS in 1985... so there's that.
All my math is done on a calculator now.

 

Thread title corrected