Why Does Gas Mileage Drop with New Tires?

One little-known and somewhat controversial fact about new tires they are more likely to decrease your fuel economy than any other time during the life of your tire.

This phenomenon is commonly referred to as “rolling resistance.”

How New Tires Increase Fuel Consumption According to a study by Bridgestone, tire pressure has a direct impact on fuel economy. As the pressure in the tires drops, so does gas mileage. The effect isn’t insignificant either. On average, a drop in pressure of 2 psi can increase rolling resistance by around 3 percent which could mean an extra 3 miles per gallon for every 10 psi drop.

Do new tires affect gas mileage?

New tires affect gas mileage for two reasons. First, the newness of the tire introduces materials and layers that are stiffer than they will be as a tire wears in.

This means that they drag against the road harder, increasing fuel consumption by between 3 and 8%. And though you may not think so, air actually weighs something too. As a tire loses its air pressure, it also loses some of its mass –which also increases rolling resistance and decreases gas mileage.

This effect is more pronounced in trucks or other commercial vehicles with larger tires or higher load ratings. Why? The weight of the vehicle is spread over a larger number of rotations, thus increasing fuel consumption on a rate basis.

How much does tire size affect gas mileage?

Smaller tires affect fuel economy more than larger ones. The reason is simple, according to Bridgestone engineer David Gassman: “When a car owner replaces a worn-out tire with an equivalent, but the larger one, the difference in rolling resistance between these tires is very significant.”

Bridgestone generally recommends that drivers replace their tires at the 15,000-mile mark. So that means that new tires introduced at 2,000 miles could cause an average of 6 percent decrease in fuel economy.

The Effects of Rolling Resistance

One might guess from the above that rolling resistance has a direct impact on fuel consumption through loss of gas mileage.

Which tire is better for fuel efficiency?

This is a trick question. The answer depends on the amount of weight being carried and how many miles are being driven, not just the type of tire.

While fuel consumption increases with gas mileage, this doesn’t mean that single-axle vehicles do better with less fuel-efficient tires and larger ones for vehicles with a heavier load.

On the contrary, in many cases, it’s better to maximize tire pressure to get the most out of your vehicle’s tires. This is particularly true if driving in a real-world situation where loaded trucks also travel at higher speeds and thus consume more fuel than unloaded ones.

How can I improve my fuel economy with Tires?

The most important way to reduce rolling resistance is to maintain proper tire inflation pressure (listed on the side of each tire). There are two easy ways to measure this: use a digital tire pressure gauge, or buy a gauge with an LCD display that tells you what your current pressure is.

If you don’t have either of these simple options, use the penny test. Insert a penny into your tire’s air valve. If you can see all of Lincoln’s head, your tires are properly inflated. If you see his neck or above in any of your four tires, they’re under-inflated and need air.

What is a good fuel efficiency rating?

The EPA fuel economy ratings are based on laboratory tests in which the car is driven at a steady speed of 50 mph and the air conditioning is on. The test makes use of a device called the Rolling Resistance Tester, which rolls along beside the car and measures resistance in terms of miles per gallon.

A second tester called the Accelerating and Decelerating Calibration Rig measures energy consumption when accelerating or decelerating. These measurements allow engineers to calculate how many miles can be driven for each gallon of gas using a more complex formula than simple miles per gallon (MPG).

Fuel efficiency is going to depend on the type of vehicle and engine used in a car, for example, an SUV vs a normal Sedan car gas mileage will vary, so it is not a one size fits all answer.

How much do bigger tires affect gas mileage?

Newer Pickup trucks often have larger tires that provide better traction when carrying heavier loads. These tires increase rolling resistance, which means additional fuel consumption. The effect isn’t significant enough to cause concerns for owners of less than 8,000-pound vehicles, but they should be aware of it.

An unpublished 2003 study by the University of Michigan Transportation Research Institute found that a 10 percent increase in rolling resistance caused a 0.6 percent drop in fuel economy for full-size pickups with eight wheels and above.