If your car's tires need changing, you may have found a good deal on a set that is a little smaller than what your vehicle calls for. While you may be tempted to take the deal, know that the size of the tire for your particular car's make and model is part of the vehicle's overall design. If you put tires on your car that are too small, this could cause a couple of issues.

1.  Inaccurate Readings for Both Speed and Mileage

One issue that is often caused by having tires that are too small for your car is that the decreased size can affect your dashboard instrument readings. This is particularly true for speed and mileage readings.

When your car was designed and built, the instruments were calibrated for a certain amount of tire rotations per minute. However, because smaller tires will spin more while driving, they will have increased rotations per minute. Because the tires are rotating faster, your speedometer will likely tell you that you are going faster than you should be. This higher reading could make you go slower than is safe on a busy, fast-paced road.

As far as your mileage, this reading will also show higher than what it should be when you have smaller tires. Not only could this make it difficult to determine the miles spent on a trip, but when you decide to sell your vehicle, it can also make it appear as though your car was used more than it actually was.

2.  Decreased Performance of Traction and Braking Systems

Another problem with using smaller tires on your car is that they will affect the performance of the traction and braking systems of the vehicle. The brakes and drivetrain of the car were calibrated and measured for use with the tire size that is recommended for the make and model.

However, if your tires are too small, your vehicle will most likely not have as good of traction as it normally would—especially on wet roads. And, since the brakes are the wrong size for the tires, you may find it difficult to stop without the car pulling or stuttering.

Ensuring that you use the proper tire size for your car can give you more accurate instrument readings as well as help to keep you safer while driving. If you are not entirely sure as to what size you need, take your car to an automotive tire dealer (such as Brogan & Folz Firestone) to ask for their assistance.