I understand bigger tires take more energy to get moving and are heavier, but it also travels further per rotation… acting like a “larger gear”.
With this being the case, it should improve fuel economy or work out to be pretty much unchanged. (At least on freeways), right?
In: 5
Yes, you’ve got it right. “on the freeway” part is correct. If a vehicle spent most of its time at constant speed on fairly straight roads, a larger tire would indeed improve fuel efficiency.
Real life driving though is mostly accelerating, braking, turning and that is where higher friction, greater moment of inertia etc work to reduce fuel efficiency. Properly sized tires also balance driving habits of most people with the engine output curves. If larger tires make a driver use more accelerator and drive the engine harder – this also reduces fuel efficiency.
The biggest factor in driving fuel efficiency is the organ that sits between the ears of the driver. Larger or smaller tires make a difference but not as much as driving style and attitude.
Accelerating slowly, anticipating when to slow down, keeping at speeds under 90km/hr etc do far more for fuel efficiency.
They don’t always reduce economy but the why is complicated (many factors at play).
Inertia matters when you’re accelerating the vehicle, that costs economy. A larger tire might gear a vehicle to a more efficient operating regime. Compari g two of the same diameter, a tire with a taller sidewall (and smaller wheel) might be lighter and use less energy tocaccelerate than a large wheel amd short sidewall. That larger tire might be an off road model that is softer and has more rolling resistance (the tire flexing absorbs energy and heats the tire). The large tire might be used because it is narrow and aerodynamic (like solar powered racing cars or maximum efficiency competition vehicles use bicycle wheels and tires because they have very very low rolling resistance.
Tire compound, belting, tread pattern, temperature, load sensitivity, surface roughness, roadway material, etc all influence the efficiency too.
Latest Answers