hodown

Hey everyone,
I just got a new '13 5.0 3.55Gears RCSB. I'm at 4200miles now.
When I bought the truck I was averaging 19.8-21.1MPG. Which is AWESOME.
So heres the problem. I put on some new FX wheels.
Stock tire size 265/60 R18
FX wheels 275/55 R20
My MPG now is 14.8-15.7 MPG for 3 tanks now.
Can this change in tire dimension really drop the fuel mileage that dramatically???
Thanks in advance.
Chris

CaSCrew11

That tires are about 1.5 inches of additional total height over the stock wheels. The big thing would be to weigh each set-up. The 20's prob weigh more, but I wouldn't think it'd be enough to lose MPG's like those?! You have one of the lighter configurations of cabs, and so I'd imagine your mileage to be about as close to EPA ratings as they come in stock form.

NorthernYankee

Did you re-calibrate your speedometer?

hodown

I knew it would go down. But not that much either. No recalibration yet. I calculate the MPG. The dash reads pretty accurately still.

engineermike

That's because the dash uses the same wrong distance data that the ODO does. Recalibrate and you'll gain about 5% on both.

SkiSmuggs

+1