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1999frontier
09-14-2012, 08:30 AM
I was wondering if someone knew a calculation or what they thought my MPG is now that I've put bigger tires on my truck. OEM was LT245/75/16 and I put LT285/75/16. I didn't get the speedometer reconfigured and the other day I reset my in dash display to see what the MPG was and after three days its showing 11.2 MPG. This is all city driving about 3 miles to work, back home for lunch, back to work, and then back home so about 12 miles aday during the work hours. Then I will pull the trailer a couple days a week, no more than 20 miles in an afternoon. So with the new tire size am I getting about 10 mpg or how can I figure?

GreenI.A.
09-15-2012, 12:46 AM
There are way to many variables to do he math on what your mileage will be with the change of tires. You can do the math on the size of the tires, if the new tire's circumference is 10% larger then you will cover 10" more ground with each spin of the wheel, that is how the speedometer reconfiguration work. Theoretically one would think this would also work for fuel mileage. In reality though the increased weight of the larger tires and increased friction from the larger surface area will cut your mileage, much like how putting weight in the bed or pulling a trailer will do.

Your best bet to get the actually mpgs is to just keep track with the dash display. Or fill your tank then do your normal driving with the trailer for a couple days, then refill your tank. Take the miles driven and devide by the amount of fuel used.