Regardless of where you get new tires, there are a few things you should keep in mind:
1- Know the size and type of tire recommended by your owner's manual.
2- Determine your needs and priorities. What type of driving you will be doing? Do you prefer a soft ride, a firm ride, or a mix of the two?
3- Make sure you purchase a tire that is capable of supporting the load your vehicle might demand. Don't buy a passenger-car tire if you need a light-truck tire.
4- Don't buy more tire than you need. Consumers often overestimate their tire needs. In most cases, a quality all-season tire will suffice where a touring tire might be suggested.
5- Keep in mind that any tire selection is a balance between ride quality, noise suppression, fuel economy, wear, load capability and cost. It's the job of the tire-store expert and the consumer to select a tire that is the right balance of each.
Source: Howstuffwork