Test the tires.
Vehicle safety starts with the tires. “Don’t be fooled into thinking that grooves and tread are for wet traction only,” AAA lead mechanic Alonso Ramos says. “Think about a pair of shoes. Do they perform well when they are worn?”
The minimum thickness considered safe by most tire manufacturers is 3/32 of an inch, and wear indicator bars show when it’s time for new tires. These flat rubber bars are nested in the deepest grooves on the tread, and they get easier to spot as the tread wears down. When the indicator bars are nearly flush with the surrounding tread, it’s time to replace the tire. Inspect the tread all the way across and all the way around each tire—if the wear is uneven, it could indicate that your wheel alignment is off. Most manufacturers recommend replacing tires six years after their production date, regardless of tread wear. Extend the life of your tires by keeping them at the recommended air pressure and rotating them every six months or 7,500 miles.
When tires are underinflated, they wear more quickly, are more likely to fail and cause a crash, and can adversely affect fuel economy. Built-in tire pressure monitoring systems are effective at alerting you to unexpected flats and dangerously low tires, but they only warn you when pressure is 25 percent or more below the recommended pressure, which is well below optimum for daily driving.
The proper pounds per square inch (PSI) for your vehicle’s tires can be found on the side of the tire as well as on the driver’s-side door jamb if you are still using the original tires. Tire pressure should be checked at least once a month with a digital tire gauge, which costs $10 or so and fits in the glove box. It’s best to test the pressure when the tires are cold (because the air inside is at its most compressed).
When refilling cold tires, inflate to the PSI recommended on the tires. When refilling warm tires, inflate to about 80 percent of the maximum PSI listed on the tire (for example, if the maximum PSI listed is 40, you will multiply that by 0.8 and fill your tires to 32 PSI). Overinflated tires can be damaged more easily by potholes or road debris. Remember to check—and top off—your spare tire if you have one.