When it comes to replacing your tires, unless you are a mechanic or very familiar with tires, you are likely to go with whatever the tire dealer gives you. This isn't necessarily a bad thing, especially if you go to a trusted dealership. However, if you would like to be more involved in the process and have a greater understanding and input on what tires go on your vehicle then understanding tire ratings is a good place to start. To create a standard for tire quality and performance the National Highway Traffic Safety Administration ( NHTSA ) created the Uniform Tire Quality Grading System (UTQGS). This system measures the treadwear, traction, and temperature of all tires and all brands as well as requires it to be printed on the tire's sidewall. Treadwear ratings measure the approximate wear rate of tire tread . The control tire is given a rating of 100 and all other tires are then compared against the control; the higher the number the longer the wear rate. Most tires are rated between 200 and 600. Traction ratings are done to measure a tire's ability to stop on wet asphalt. They are rated from highest to lowest as follows: AA, A, B, C. Naturally the tires with higher rates have a shorter stopping distance than those with a lower rating. Given their composition, tires tend to deteriorate over time even with proper maintenance . When exposed to sustained high temperatures, like taking a road trip in the middle of the summer, that process is accelerated; which can lead to blowouts and other tire damage. To measure a tire's heat resistance they are given a rating of A, B, or C; with A being the highest and C the lowest. These ratings are an important part of understanding what quality of tire you are getting but it's always important to take into consideration your personal driving habits, where you live, etc.