How Wider Tires Effect a Car's Fuel Economy and Handling

Tires, regardless of size, can make a difference in fuel economy through the construction of the tire. The effect on fuel economy is not monumental, but prevalent. The quality of the tire determines the thickness and stiffness of the sidewall of the tire. The more material used and the stronger the bead in the sidewall of a tire reduces the flexing of the tire. The stiffer sidewall makes a world of difference in handling since the tread patch remains in contact with the road surface even in hard turns. With a soft sidewall tire, serious flexing or bending toward the opposite side of the turn are experienced. When this happens, much of the footprint is not in contact with the road and the vehicle is, in essence, close to riding on the sidewall. This flexing effects fuel economy. The stiffness of the tread is another factor. More and stronger steel belts also help in keeping a flat footprint.Sizing of tires:

The numbers on the side of the tire represent tire sizes. For an example, a 225/60/16 embossed on the side of the tire translates to 225, which is the width, 60, which means the tire is 60% as tall as it is wide, and 16 is the size of the wheel that it fits on. Tires can be purchased that are either wider or narrower than original while still keeping the same height, which is the most important. To increase the width of the above tire, simply increase the first number, which is the width by two increments to 245. Drop the second number, which is height to width ratio by one increment to 50, and keep the wheel size the same. Now a 245/50/16 is the same height as a 225/60/16, but wider. Conversely a 205/70/16 is narrower yet the same height.Effects of tire size:

The width of a tire makes no discernible difference in fuel economy. Width however makes a huge difference in the handling of a vehicle. The wider the tire, the larger the footprint on the road. Height of a tire makes a major difference and can adversely effect the operation of the vehicle. The height of the tire changes the final gear ratio. All late model vehicles are set up from the computer to transmission for a certain size tire for the proper gear ratio. A change throws all computations off. The speedometer and speed sensors will not send the correct speed signal to the transmission and shifting points will change. If the tire is higher, the torque level will be reduced as well as the RPM at speed. Many areas will change and conversely if the tire is smaller, the reverse will take effect.Load rating on tires:

It is always a good idea to check the owner's manual or a tire guide at a tire store for the recommended load rating for the vehicle. Tires all have different load ratings. A tire with a lower load rating would be hazardous.Determination of acceptable increase in width:

The owner's manual or the tire guide is the best source for this information. The manual shows a chart with widths that will fit under the vehicle without interference when turning or hitting bumps on a rough surface. If a tire is too wide, it will strike the inner fenderwell and rub in a turn and the rear tires may interfere with the fenderwell when on a rough road.Offsets for wider tires:

On many vehicles, if a wider tire will not work because it protrudes from under the fenderwell, a new wheel with a different offset can be purchased that will keep the tire under the fenderwell by moving it in a certain amount.