Irregular tire wear not only means that you need to buy new tires, it's a sign that something else is wrong. If you don't get the underlying problem resolved, new tires will also develop abnormal wear patterns and a loss of longevity. Consider the types of issues that can lead to tread wearing in noticeably unusual ways.
This is the easiest problem to fix. If you tend to judge tire pressure by eyeballing the tires, it's time to buy a tire gauge and use it. Under-inflated tires tend to wear more along the edges because the tire is essentially sagging instead of riding normally. Over-inflated tires wear more in the middle because the edges lift off the ground.
Correcting the tire pressure now won't reverse the current problem with irregular wear, but it's still important to do it anyway. Tires with too much air have less tread on the road and thus, less traction. Reduced traction can cause problems with handling and braking, especially on roads that are wet or have snowy or icy patches.
Not Having Tires Rotated
If you never bother to have your tires rotated, they will likely wear unevenly because more wear develops on the tires in the back. Follow the vehicle manufacturer's guidelines on how often to get rotation service.
Wheels Out of Alignment
Typically you can tell if the wheels are out of alignment by driving on a straight, flat road and letting go of the wheel. The vehicle should continue to travel in a straight path. If it drifts to one side, the wheels may not be aligned properly.
A Worn Component in the Steering or Suspension System
Worn parts that run from the wheel to the car can cause irregular tread wear. Typically, the driver can observe signs of specific problems.
Worn shocks and struts, for instance, can cause the vehicle to sway when going around corners. When going over a bump or dip in the road, they might make scraping noises or cause one end of the vehicle to bounce up and down.
Worn suspension bushings can make clunking noises, while worn wheel bearings may produce grinding sounds.
What You Can Do Now
Get the underlying problem resolved before you buy new tires. Then bring your vehicle to a place that sells a wide variety of tires so you have several brands and options from which to choose. The sooner you can get new tires, the better, since worn tread is a safety issue. Contact a company like Dial-A-Tire Inc to get started.