The first thing you should do with your new car is determine what kind of tires it came with. Are they all-seasons with 60,000-mile warranties or performance tires that will be gone in 20? Some dealerships, particularly in the South, sell cars installed with summer tires, which are designed for long tread wear and a quiet ride but not at all for snow or ice. Such tires are fine for those climes and handle terrifically in the rain, but if you head North at all during the winter, beware.
When considering a tire upgrade along with a possible increase in wheel diameter, be cautious. Putting 22- or 24-inch wheels on your SUV, while flashy, adds up to 400 pounds of unsprung rotational weight, decreasing acceleration times and increasing stopping distance up to four car lengths. You should compensate for this with new brake pads and possibly larger rotors and calipers. When upgrading as a performance enhancement, increasing wheel diameter will increase your performance, but only up to a point. If you go from 15 to 16 inches, or 16 to 17, each step makes the car corner faster, since a shorter sidewall is stiffer than a taller one, and the driver can read the road much faster. Beyond 18 inches, the tire sidewall becomes too small for comfortable driving.
Driving on properly inflated tires is critical to fuel economy, vehicle performance and tread wear. In 2008, tire-pressure monitors will become mandatory for all cars sold in the U.S., but drivers must remember that the systems notify them only when the air pressure is too low by 25 percent. That 25 percent is critical--it's where the real advantage in fuel economy and proper tire wear takes place. Furthermore, according to John Rastetter, director of product information at the Tire Rack, an online tire retailer that conducts extensive in-house testing of tire products, tire manufacturers, many of which oppose the legislation, are concerned that a 25 percent drop in tire pressure may be unsafe, because underinflated tires may not adequately support a fully loaded vehicle. "Even if you do have a tire-pressure-monitoring system in your car, don't rely on it exclusively," Rastetter advises. "Still check the tire pressure at least monthly to ensure that they aren't riding even a few pounds low."
If you get more than two or three substantial snowfalls a year, seriously consider snow tires, which are specially designed to grip snow on the pavement. "Traction in the snow is a partnership between the road and the tire, or the snow and the tire--or, in reality, the snow and the snow," Rastetter says, explaining that snow-tire traction is achieved when the snow that is gripped and retained by the tire's tread interacts with the snow on the pavement. Instead of buying snow tires and switching them onto your existing wheels every winter--and paying to have them mounted and rebalanced--consider buying a set of snow tires already mounted on inexpensive wheels. You can then put them on yourself and, in the process, spare your nice alloys the abuse of winter driving.
Rastetter also recommends rotating the tires front to back every 3,500 miles up to the 15,000-mile mark on your odometer. Thereafter, rotate every 6,000 miles up to 30,000 miles, and then every 4,000 miles up to 60,000 miles. Tires wear faster when they're new and toward the end of their lives, so you want to rotate them more often during these periods.
Ultimately, your tire performance is mostly a function of what kind of roads you drive on--tire grip and tread wear are directly related to the quality of the local roads. Rastetter notes that asphalts vary from state to state because they're all made from local materials. In Hawaii, for instance, where roads are made from abrasive volcanic pumice, tires have more grip, but they wear out faster.