Where the Rubber Meets the Road
What do you need to know about buying new tires for your car?
I drive a 1992 Honda Accord, mostly within that hazy zone that is the speed limit. I don't corner aggressively or attempt 180-degree emergency-brake power-spins. So, what am I looking for in a tire? I want something that's reliable and worth the money I paid for it.
To get a tire education, I grilled a few auto mechanics and pored over informational Web sites. Then I went to a real expert, Daanesh Chanduwadia, who develops training materials for automotive dealer technicians. Daanesh used to manage a shop specializing in performance enhancements for European automobiles, and he says he has read and studied everything car-related he could find since 1984. But all this is more than you want to plow through, so below are the essentials—what you need to know.
When To Replace Your Tires
Daanesh begs you to accept the fact that your tires are disposable. They work right for a while, but then the longer you wait, the worse they perform. So have them checked often. If your mechanic says it's time, do listen, because worn-out tires ain't worth squat in the rain. A rule of thumb: If you can stick a penny edgewise into the grooves and still see all of Abe Lincoln's head, your tread is worn down to a thickness of 2/32 of an inch, and your tires are illegal in most states. You should replace well before you reach this stage. Your tire's performance is heavily compromised at this point, and the tire won't pass inspection.
All-Season or Summer?
Once you know that your rubber needs to go, it's time for another decision: all-season or summer tires? It's a crucial choice. Performance on snow and on dry pavement are two conflicting goals (almost mutually exclusive) and require very different tire designs. So, if you never ever see snow where you live, get summer tires—they'll handle better. But if you do drive on snow, even occasionally, get all-season tires. You need their treads if you want to get traction and lead a safe and productive life.
You do sacrifice a little with all-seasons. They aren't as impressive on dry pavement, though they still do fine. In a perfect world, you'd switch tires twice a year to fit the weather, but I'm assuming you're lazy and cheap like me and thus won't even consider this, and hey, that's cool—I'm not judging you.
(By the way, if you drive through thick snow all the time, you need real snow tires, not just all-seasons. But hearty souls like you already knew that.)
Reading a Tire If this is a newish car getting its first tire change, you'll be removing the "original equipment" tires—the ones the manufacturer put on. can help you decide which new tires to buy. Regardless, you should learn how to read a tire.
On your tire's sidewalls, you'll see lots of markings. One of them refers to size. On my Accord, the O.E. tires were marked "185/70-14": 185 is the width of the tread in millimeters; 70 is the "aspect ratio" of sidewall height (measuring the edge of the rim to the road) to that width; and 14 is the diameter of the wheel (equal to the hole in the center of the tire) in inches. The format is the same on most tires. You don't need to remember what the numbers mean, but you want to stick with the tire size you have. You can look up O.E. size for your own car (make, model, and year) on the fantastic TireRack.com.
Next, look at the speed rating on your old tires also stamped into the sidewall. This is basically the tire's maximum speed, but also hints at its total performance. Common examples include SR (112 mph), TR (118 mph), and HR (130 mph). You want a speed rating as high as or higher than the one on your O.E. tires.
I know what you're saying: "Jeepers, I never go over 70!" No matter. Cars designs rely on a certain level of tire quality, so if you swap in something lame it can be dangerous. Also, a high-speed rating gives you wiggle room. Says Daanesh: "If you do something boneheaded in a corner but it's only half of what your tire can handle, you're fine. If it's 99 percent of what your tire can handle, who knows …" Higher rated tires are stiffer, so they're tough to blow out in a pothole, but they make the car's ride a bit harsher. And they don't last as long.
Also on the sidewall: UTQG ratings (Uniform Tire Quality Grade). These are ratings for traction (a grade of AA, A, B, or C, based on straight-ahead wet-braking tests), temperature resistance (A through C based on how much heat the tire can take), and tread wear (a number suggesting how long the tire will last). The tread wear rating is notoriously misleading, so you should probably ignore it.
Finally, look for the "M + S" mark. This means Mud and Snow, and if it's there you've got an all-season tire. If it's not there, it's not an all-season tire, no matter what the mechanic tells you.
So, when you get to the store and the salesman points out a tire mounted up on the wall, go look at all the info stamped there. If you don't understand something, have it explained. Know your sidewall markings!
Land and Sea
Now swing your eyes from the sidewall over to the tread. Divide the tread pattern into "land" and "sea," so that land is the rubber that sticks up in plateaus and sea is the spaces in-between. Lots of land without much sea means the tire works better on dry pavement—plenty of grip against the road. Lots of sea means the tire is designed for wet conditions—plenty of room for water to channel out. Longitudinal bands of sea help prevent hydroplaning. Horizontal strips of sea provide traction in the snow. Diagonal sea will help with cornering in the rain. Finally, "sipes" are lots of little horizontal cuts that also help with traction. (Sipes are good if they're part of the tire's design, but if someone offers to sipe your tires for you, politely decline. It can compromise the design of the tire. If you really need more traction, it's better to spend that money on tires with a better design.)
Enough Already, What Do You Recommend?
OK, maybe you didn't need to know all this and just want some recommendations. Daanesh was happy to oblige with a few off-the-cuff picks.
First, the brands. When it comes to all-season tires, Daanesh says to stay away from BFGoodrich, Cooper, Uniroyal, Goodyear, and General. They don't make anything in this category that you want on your car. Why? Without getting too technical, they use lesser technology, less-ingenious designs, and inferior compounds. Acceptable brands: Yokohama, Dunlop, and Pirelli are good, though Pirellis wear out quickly by design. Don't be totally scared of Firestones unless you drive an SUV—some are good, some are less good. Bridgestone is better than all of these—a very good tire.
But the class tire of the group is Michelin. Michelin has a good reputation, and it's used as the O.E. tire on cars with good reputations (BMW, Ferrari, Porsche). That's not a coincidence. Michelins are known for their ride comfort and their low failure rate. Because of strong, longitudinal bands of solid rubber, they tend to "know where straight is," in the lingo—they won't cause your car to drift.
As for specific tires: If you're an average driver like me, in an average car, in an all-season climate, Daanesh's major pick is the Michelin X-One. It has generous water channeling but a good amount of rubber on the road. Its sipes help get traction in slush and snow without sacrificing too much in dry weather. The Achilles heel: cornering in the rain. But most people automatically slow down when cornering in rain, so the tire's weakness is offset by this tendency. Still Daanesh felt he should add that "in an evasive situation, the Michelin might rear its ugly head." (Follow-up questions for Daanesh: Dude, how many "evasive" situations do you get into? And can I ride shotgun?) The X-One goes for $72 a tire on TireRack.com for my Accord; for other cars the prices vary.
If you're willing to spend a little more, you can move up to a "touring" tire, which is a hybrid between a standard and a high-performance tire. It has better technology and performance, without sacrificing noise levels—a drawback of top-shelf, sportier tires—or longevity. (Touring-type tires come standard on Mercedes and Lexuses.) In this class, Daanesh recommends the Michelin MXV4 Plus, which goes for $116 a tire for my Accord on TireRack.com, though prices will vary from outlet to outlet.
But no matter where you buy, remember to figure in the cost of installation for each tire. And don't buy tires one at a time. Buy in pairs or fours, or your handling will be uneven. If you buy a pair, put them on your rear wheels. Most shops will put them up front because the front wears out faster, but if one end is going to lose grip, you'd much rather it was the front—the slide will be more controllable than if the rear wheels were swinging around. Also, don't pay attention to tread-wear warranties that guarantee the tire for a given mileage. Remember, tires are meant to wear out. A warranty just locks you into buying more of the same brand.
Finally, all this is meaningless if you don't maintain proper tire pressure. Use the guidelines listed for your car, not for the tire: The same tire can be used on lots of cars of varying weights, so listen to what the car says. And be vigilant. Low pressure will defeat the entire design of the tire.
Seth Stevenson is a frequent contributor to Slate. He is the author of Grounded: A Down to Earth Journey Around the World.