An often ignored and overlooked cause of reduced fuel economy is the type of tire a person is using. Standard M&S tires (mud and snow) which are considered all season tires are the standard on most production vehicles. While they provide the best compromise between long tire life, and ability to drive in snowy conditions as well as dry they are not the most efficient tire design at increasing fuel economy.
The difference between all season tires, pure winter only tires and summer performance tires is found in their equivalent tread and rubber designs. Generally, winter tires are designed to grip the road as much as possible and provide as much friction between the road surface, snow, ice and the tire as possible. This prevents you from slipping in the winter and provides more traction during snowstorms. The downside to this increased friction with the road surface is a dramatic drop in gas mileage as the vehicle can not accelerate or roll as freely as it would with less frictional tires. So gas mileage suffers. All season tires are a good compromise between winter tires and summer only tires. They provide middle of the road gas mileage and performance.
In order to optimize your gas mileage, running summer performance tires is the way to go. Unfortunately you cannot use these tires in the winter on snow or ice as they are not designed to handle travel on slippery surfaces and will be extremely dangerous if you do so. Summer performance tires are meant ONLY to be used in Summer, Spring and possibly Fall seasons. Summer performance tires use a special combination of rubber and stiffer base materials to make the overall tire compound extremely stiff as compared to M and S tires which means there is much less deflection of the actual tire as it is weighted down by the car contacting the road surface as you are driving. The net result is much faster acceleration as less of the vehicle’s moving kinetic energy is absorbed into the deforming tire surface and instead transferred into forward motion of the car itself.
This translates to increased acceleration and if you are consistent with the same throttle application as you used to use before you changed to summer performance tires, you will realize fantastic positive increases in your gas mileage. As it will take much less energy to move your vehicle the same amount of distance.
Unfortunately there is also a cost downside to summer performance tires. They tend to be very expensive as compared to regular all season tires and also do not last nearly as long. So one must weigh the extra cost of the tires and the reduced tread life against the resulting net gains in fuel economy over the life of the tire.
Remember: NEVER USE SUMMER PERFORMANCE TIRES IN THE WINTER!! It is very dangerous and unsafe to do so. Always follow your particular tire manufacturer’s guide for how to use your tires, in what seasons, under what temperature conditions, and what tire pressures.