Can tires really affect gas mileage?
Can tires really affect gas mileage? The short answer: yes. Tires can make a big difference in the number of miles a driver gets to a tank of gas. And it’s not all about tire maintenance; even the kind of tire on the car can affect the fuel economy. It all comes down to rolling resistance, how the tire overcomes inertia.
What is rolling resistance?
Put simply, rolling resistance is the force that resists motion between the wheel and the surface. But there are a lot of factors involved in rolling resistance and fuel economy, such as inertia, road quality and air drag. Changing the tires won’t deal with all of them.
Rolling resistance doesn’t stay constant either. As other factors that affect fuel economy are eliminated, rolling resistance plays a larger role. So fuel efficiency is different during steady-speed highway driving as opposed to stop-start driving in traffic. As vehicle designs became more aerodynamic, rolling resistance has a greater role to play in fuel economy.
Vehicle manufacturers have certain average targets to meet on fuel efficiency across each year’s production. Most manufacturers develop low rolling resistance tires as stock. These tires are often designed with a priority on reducing weight and are molded with slightly thinner sidewalls and shallower tread depths and use low rolling resistance constructions and tread compounds.
Treadwear and fuel economy
Much of the rolling resistance of a tire, about 35-50 percent, comes from the tire tread. Bridgestone Tires has a great breakdown of tread compounds. Some compounds, especially those incorporating silica or using formulas that combine natural and engineered synthetic rubber, can reduce rolling resistance a great deal. The shallower the tread, the more fuel efficient the tire will be. So if you can achieve traction, the more fuel-efficient tires might be shallow-tread rib designs.
Tire size and gas mileage
It’s easier to get a smaller wheel and tire moving than a larger one, so in stop-start traffic the smaller would be the better option. Less power is needed so you will get better mileage. But once moving, the engine works harder to make the smaller wheel cover the same distance as a larger one. So for better fuel economy when cruising, the larger wheel would be better.
However, there’s also weight to take into consideration. Some good advice on tire size and weight is for every inch you add in wheel size, compensate by reducing the height of the sidewall. Keep in mind that this will also affect your load capacity.
The easy solution: tire inflation
If all of this is getting a bit complicated, it’s understandable. A simple takeaway point for your customers is that the easiest way to enhance fuel economy is to make certain their tires are properly inflated. According to Fuelman, a tire that is 20 percent underinflated can increase a vehicle’s fuel consumption by 10 percent. Underinflation also increases the rate of wear on tires, which can mean they’ll need new tires sooner.