Tires speak, and they are worn out
Did you know that tire's wear their wear on their sleeve? Most tires include a simple tread-wear indicator molded into their tread rubber that indicates when a tire is worn to its legal 2/32" (1/16") limit. When the tread rubber is worn evenly with the bar, it's time for new tires. If you're in an area where poor weather is common, your tires may tell you they need replacing even before they reach the legal limit. If you suddenly seem to be hydroplaning through the same puddle you traveled through every rainstorm without incident or if climbing your snow-covered driveway is more challenging than it was last year, then it's likely that the worn tire tread is preventing the tires from dissipating water or gripping as they once did. In our tests of all-season tires that were only half worn, we found hydroplaning resistance and winter traction were significantly reduced.
How a tire wears can be nearly as informative as when a tire wears. If a tire's edges or shoulders are wearing faster than the center, there's a good chance that the tire has been run under inflated, which tends to put more weight onto a tread's edge. If the wear in the center appears more than on the shoulders, just the opposite is true and you may have too much air in the tire.
When one edge is wearing more quickly than the other, it often indicates that the car needs an alignment or perhaps suspension components are worn and need replacing. --Gene Petersen