random thought on big tires

[ticopowell]

So from what I have read, and what I understand about putting on oversized tires on a truck, it essentially changes the gear ration, and makes it so less power gets to the ground. I also understand that if you have a lower gear ration (3.55 being lower than 3.73), you get better gas mileage in the truck because the engine works less at higher speeds. so since lower gears add gas mileage, and big tires make the effective gear ratio lower, if we ignore other factors like aerodynamics and heavier and harder to turn tires, you should get better gas mileage? is this right? or do the weight and lack of power to the ground make enough of a difference to negate any gear ratio improvement?