I shared my new Lariat back in December when I first got it. Since then, I’ve leveled it and added 34” Nittos.
Some folks were curious about the MPG, so here’s a pic of the screen after a weekend road trip.
The good news? The truck is incredible, and I still can’t stop admiring it. The bad news? The gas mileage is terrible! 
Did you adjust the odometer for the new wheel size? If not, your numbers might be off.
Wynter said:
Did you adjust the odometer for the new wheel size? If not, your numbers might be off.
Good question! I don’t think it was adjusted, but I’ve checked against highway mile markers, and it seems accurate. Could it still be off?
@Vale
I’m not sure how the newer models handle it, but older trucks based it on tire rotation. If that’s still the case, you’d need to adjust it or do the math manually.
Formula:
New tire diameter ÷ Old tire diameter = Y
Y × Miles driven = Z
Z ÷ Gallons used = Actual MPG
Example:
34/32 = 1.0625
1.0625 × 708.5 = 752.781
752.781 ÷ 45 = 16.7 MPG
So you might be getting about 1 MPG more, depending on stock tire size.
@Wynter
You’re a lifesaver! I was trying to figure this out over the weekend. Funny enough, I just rewatched ‘Stand and Deliver,’ so I felt extra dumb not knowing the math for this. 
Ben said:
@Wynter
You’re a lifesaver! I was trying to figure this out over the weekend. Funny enough, I just rewatched ‘Stand and Deliver,’ so I felt extra dumb not knowing the math for this.
Glad to help! 
@Vale
You could use a GPS speedometer app to double-check.
@Vale
708.5 miles at 15.7 MPG would mean a 45-gallon tank fill-up, minus 91 miles. The 2024 PowerBoost tank is 30.6 gallons.
@Vale
You can also use Google Maps with CarPlay—just start navigation, and it’ll show your speed.
This thing is a beast! Everyone told me I’d love it, but I didn’t expect this big of a difference.
To be upfront, I’m not a hardcore truck guy who knows every detail inside and out. I just wanted something solid to escape my corporate life—and I have no regrets!
I was torn between 33” and 34” tires for my 2020 Lariat… You just convinced me to go with the smaller ones. Appreciate it!
Kavi said:
I was torn between 33” and 34” tires for my 2020 Lariat… You just convinced me to go with the smaller ones. Appreciate it!
Yeah, after seeing people post 17 MPG with 35s, I’ve been looking for the lightest all-terrain LT-rated tires. Thinking about Firestone Destination XTs in 275/70/R18—they’re only 50 lbs compared to the 70 lb options.
@Charlie
I’ve got those exact tires, and I’ve been really happy with them. At 37K miles, they’re about halfway worn. I’m getting around 17-18 MPG on the highway.
Fallon said:
@Charlie
I’ve got those exact tires, and I’ve been really happy with them. At 37K miles, they’re about halfway worn. I’m getting around 17-18 MPG on the highway.
What PSI are you running? I was thinking around 43.
@Charlie
Yeah, I tried to find the lightest E-rated ATs, but these trucks are really sensitive. I run anywhere from 38-42 PSI, depending on the situation.
Kavi said:
I was torn between 33” and 34” tires for my 2020 Lariat… You just convinced me to go with the smaller ones. Appreciate it!
Honestly, 33s fit the wheel well perfectly. My biggest pet peeve is when the tire curve doesn’t match the fender flare—it just looks off.
Kavi said:
I was torn between 33” and 34” tires for my 2020 Lariat… You just convinced me to go with the smaller ones. Appreciate it!
Glad I could help! I don’t drive a ton, so MPG isn’t a huge issue for me, but I see how it could add up over time.
