Most drivers will not need to change their vehicle's tire size. Stock tire size is what your vehicle was designed to use. These are some vehicle components affected by changing a tire size:

?Both the speedometer and odometer are calibrated based on the height of your tires. Taller tires would make the speedometer read slower than actual speed. Shorter tires would show a higher speedometer reading.

?Newer vehicles have internal computers that base calculations on the tire's height. Components, such as Anti-lock Braking Systems, could fail with a different tire size.

?Stock suspension could have additional stress with a taller tire, resulting in faster wear and/or failure. For substantial increases in tire height, you should upgrade from stock suspension.

Despite these concerns, some circumstances do require a tire size change. For someone looking to modify their vehicle, the wheels are often the first place to start. Stock wheels are often plain and don't attract much attention. When people switch their vehicle's wheels, they upgrade to a larger diameter stock wheel. These people get a lower profile tire that is close to stock tire height. Most tire industry professionals recommend no more than a 3% height difference from stock. Of course closer is better.

Sometimes there is poor selection in a vehicle's stock tire size. With common tire sizes, each major tire manufacturer offers at least several choices. Some rare tire sizes are only manufactured by a few companies. If those few tire choices don't match your climate and driving style, you might need to change tire sizes. You can often find a similar tire size with more choices.

If you insist on switching tire sizes, double check with some tire industry professionals. Your car dealer will likely try to persuade you from altering any stock specifications, but ask anyway. Check with some tire shops, but beware they might put the sale as the first priority. Another good place to ask advice is in automotive forums. Find a good forum specific to your vehicle type and ask their opinion. You'd be surprised how easy is it to find someone else who has already tried a tire size. Be aware that people on forums aren't necessarily industry professionals.

You can do your own research and try using a tire size calculator featured on various automotive websites. These tire calculators allow you to compare specifications of different tire sizes. They display the tire height, width, RPMs, speedometer difference and more. These tools aren't exact as a tire size can slightly vary from one tire model to another, but they are very good tools. So use a tire size calculator as a general guide. Then confirm your calculations with a tire industry professional. You can also find the exact measured height of each tire model if you visit the tire manufacturer's website.

When possible you should use your vehicle's stock tire size. Don't switch just because you find a good price in a different size. A lot of things in your vehicle were designed for the stock tire size. If you do have to switch tire sizes, make sure the size is safe for your vehicle.