Automatically changed fuel mileage indicator with bigger tires?

Did anyone else’s fuel mileage indicator automatically change itself? Mine used to say 420 to 450 on fill up,I don’t remember. Now with the leveling kit and 35s it says like 380 at fill up. Is this an ecu automatic adjustment?

 

It’ll automatically adjust off your MPGs. Bigger tires means less MPG, so it recalculated. If I unplug my battery, mine starts at about 600 miles to empty. After a few fillups, it settles around 410.

 

As stated, it is an estimate based on current / short term past usage. Once you throw the heavy stuff on, it knows because you’re burning the extra fuel.

 

I figured. Thanks for your input.

 

It's also miscalculating MPG due to the larger tires. Larger tire travels a further distance per revolution, but the truck still "thinks" you're going the stock distance per revolution. Same reason the computer calculated MPG is less than reality. To come up with the true MPG you'd have to hand calculate and factor in the true miles traveled as the odometer is reading lower than actual.

So basically what those above me said. Truck is getting less MPG due to the heavy stuff (and incorrect distance readings), so it calculates predicted distance of a tank of fuel based on that lower MPG.

 

Yeah, I absolutely understand the tire thing. I’ve just never seen a truck recalculate it like this. I was just wondering if anyone else’s was automatically recalculating automatically like mine, after tires.

 

It's not just a bigger tires thing. The computer relearns every so often...so if you drive it like you stole it for 2 weeks straight or doing some long distance towing event you would see the computer recalculate a lower range. Of course on the contrary if you drive Miss Daisy around for awhile the computer will give you a longer range in the DtE reading.

 

I’m not at my truck so can’t see my notes/ calculations but with my 35’s I am actually 1.9mpg higher than what reads on the dash (give or take, hand calculation put it’s right in the dash most times) and my distance driven is off by 18% could be higher), so I have to calculate that in when using the truck for work trips and getting paid mileage.

 

I think every vehicle that has a range estimation feature uses a function based on engine load/fuel injection rates and vehicle speed to calculate both your average MPG’s and tank range. The tank range is likely calculated with only the previous couple hundred miles. I can go on a 500 mile road trip, removing all city driving from at least a tank or tank and a half, and see a corresponding and significant jump in the estimated tank range.