You Might Need New Tires Sooner Than You Think

Easy tests tell you when.
Eventually, you’ll need new tires. Did you know that George Washington might be a better tire-wear tester than Abraham Lincoln?

There’s an old trick to tell when you need new tires: Hold a penny upside down in the tread. If you can see the top of Lincoln’s head, you need new tires.

America’s first president, it turns out, is perhaps a better tire tester than the 16^th. Place a quarter upside down in a tire groove. The distance from the coin’s rim to President Washington’s hairline is about a 1/8 inch. If you see more of Washington’s head than his hairline, get new tires.

Consumer Reports magazine cautions that you might need tires sooner than the penny test reveals, and that a tire with only a 1/8 inch of its tread left might not give you adequate hydroplaning resistance and snow traction.

The easiest thing to do is replace the tires with what came on the vehicle. Carmakers consider tires as part of the suspension system and therefore test them extensively for well over a year. Thus, “original replacement” tires can automatically restore your car’s ride and handling to showroom condition.

That isn’t to say you can’t choose another tire. Consult Consumer Reports, for example, or have a quick chat with our service manager for suggestions. This is especially important if you are considering a tire upgrade – that is, perhaps something larger. If so, remember that bigger isn’t always better. A poor tire size choice can degrade ride and handling, possibly lead to suspension damage over time and worse, affect speedometer function.

By learning to “decode” a tire, you’ll be better informed when you buy replacements. The first place to look is the driver’s doorjamb. There, you’ll see a sticker with the tire specs; they’re a whole lot easier to read here than from a tire sidewall! You’ll also find the specs in your owner’s manual.

A number like P225/65R17 is the tire size. The “P” means it’s a passenger-car tire even though it may be used on many SUVs. An “LT” instead of “P” means it’s a “heavy-duty light-truck” tire, which you’ll find on many pickups and larger SUVs.

The number “225” denotes the tire’s cross-section width in millimeters. The “65” indicates the height or thickness of the tire sidewall. This number is a ratio of sidewall height to cross-section width. Therefore, “65” means the sidewall is 65 percent as high as the tire is wide. High-performance tires will have a lower ratio such as “45,” for example. That’s what “low profile” means. Continuing, the “R” means radial-ply tire, and the “17” is the wheel diameter in inches.

The load index indicates the weight the tire can safely carry. Choose replacement tires with the same or higher load index as those that came on the car.

The speed rating comes after the load index and is expressed with a letter. “S”-rated tires allow a maximum sustainable speed of 112 mph; “T” is for 118 mph. Performance tires will have an “H” (130 mph), “V” (149 mph) or “Z” (150 mph plus). Choosing a higher speed-rated tire can give you better handling even at legal speeds, according to Consumer Reports.

The higher the tread-wear rating, a triple-digit number, the longer the tire is certified to last. High-performance tires will generally have much lower numbers than some all-season tires.

The temperature and traction scores indicate a tire’s temperature resistance and wet-stopping ability. For traction, AA is best and C is worst. For temperature resistance (how temperature changes affect tire performance), scores range from A to C. Certain performance tires may have a “low” rating of C because they are optimized for dry-road driving in warm weather.

The maximum pressure rating (expressed in pounds per square inch or PSI) is self-explanatory, but this is different from the recommended inflation pressure, which you should always follow. Your owner’s manual provides guidelines for the conditions that call for increasing tire pressure.

Finally, tires have a freshness date! Consumer Reports advises not to buy tires more than a couple of years old. Look for the Department of Transportation (DOT) number following the letters on the tire sidewall. The last four digits tell you the week and year the tire was made. For example, if you see “1509,” it means the tire was manufactured during the 15^th week of 2009.

Roll on…safely!