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Tires play a major role in the performance and safety of your vehicle. They’re responsible for how well your car accelerates, rides, steers, corners and stops. When the road gets wet, snowy or slick, your tires’ grip keeps you safe.

But over time, they wear out. They’ll have less tread depth, with reduced drainage and grip when there’s rain or snow on the road. The remaining rubber hardens as your tires age, reducing traction further. They can no longer protect you as well as they should.

That’s when it’s time to replace them, ensuring that you stay safe and comfortable for thousands of miles more. Let’s start with the most common scenario: excessive wear. Or, you can jump ahead to learn about when tires are too old, when they get damaged, and get some tips for buying new ones.

By Stephen Fogel

Replacing your tires when they’re worn down

The conventional wisdom from most tire authorities is to replace your tires when they have 2/32 of an inch of tread left. At this point, your tires are legally worn out.

There are two easy ways to check the tread depth of your tires. One is to look for the wear bars that are molded into the tire tread. These rubber bars go across the tread, and are located at regular intervals. As the tread wears, the bars come closer to the surface. When the bars are flush with the tread, you are at 2/32 of an inch, and it’s time to replace the tires.

penny test

The other way to check your tread depth is with a penny. Take the coin and pinch Lincoln’s body between your fingers, then put his head down into the tire tread. If any part of Lincoln’s head is obscured by the tread, you’re OK. But if you can see the top of Lincoln’s hair, or where it says “In God We Trust,” it’s time for you to get new tires. Check this in a few different places around the tire to get an average, then check your other tires.

When you might need more tread depth

If you live where it rains often, or you have snowy, slushy winter driving conditions, you need more tread depth. A better margin of safety for rainy conditions is 4/32 of an inch of tread, and 5/32 or more should be the minimum for snowy situations.

To check if you have adequate tread depth for safety in the rain, try the coin test described above, but use a quarter and the top of Washington’s head. If Washington’s head is at all obscured when it’s inserted into the tread in a few different places, you have more than 4/32 of an inch of tread depth remaining.

For snow safety, use the back of the Lincoln penny, and insert the top of the Lincoln Memorial into the tread grooves in several locations. If the top of the Lincoln Memorial is covered by the tread, you have more than 6/32 of an inch of tread depth remaining, which is adequate.

Replacing your tires when they get old

Age affects your tires, even if you don’t use your car a lot. The rubber deteriorates, sunlight and air pollution take their toll, and constant heating and cooling cycles age your tires as you drive.

The rubber can crack, harden and get dry rot. Internal damage such as belt separation can also make them a safety hazard.

This isn’t a big deal if you drive an average number of miles each year, say 12,000 or more. You’ll likely wear out your tires before they have age-related problems. But if you’re a low-mileage driver, or have an extra vehicle that you don’t drive much, your tires might need replacing even if they don’t look worn.

How old is too old for tires? It depends on several factors, including temperature, humidity, sunlight exposure, how much the vehicle is driven and storage conditions. Different vehicle manufacturers and tire makers have different recommendations.

The safest course is to start checking for cracking, drying and hardening when your tires reach five years old. If you’re not sure what to look for, ask your mechanic to check the tires’ condition annually. Once they hit 10 years, they should definitely be replaced.

How to tell how old your tires are

You can determine the age of your tires by looking for the DOT number stamped into the tire sidewall, on either the inside or outside of the tire. The number consists of several digits, usually nine to 10 in length, that denote the manufacturer, the plant where the tires were made and other information.

The last four digits of the code identify the date the tire was made. The first two indicate the week the tire was made and the last two denote the year. So, for example, 4816 indicates that the tire was manufactured in the 48th week of 2016.

Replacing your tires if they get damaged

Just driving around can be hazardous to your tires’ health. High curbs and deep potholes can hurt them, both internally and externally. Rocks, shards of broken glass, metal fragments and other debris can damage them, too.

It’s a good idea to visually inspect your tires every few weeks, looking for the following:

  • Cuts
  • Cracks
  • Gouges
  • Bulges
  • Blisters

Is the damage fixable?

If the area of physical damage is small enough, and is limited to the tread part of the tire, it may be fixable. Your mechanic or tire shop should remove the tire from the wheel and thoroughly inspect its inside surface. A patch, applied on the inside, may be enough to get you back on the road, and patches can last seven to 10 years, if done correctly. But if the damage is located on, or extends to, the sidewall, that can’t be repaired. You will need to replace the bad tire.

Tips for buying new tires

There are plenty of tire dealers that will sell you new tires. But how many do you need? How do you tell the good tires (and dealers) from the bad? And how do you know which tires to buy? Let’s start with some numbers.

How many tires to buy

Should you get one, two or four? It depends on how many you need and what kind of car you drive. Here are some guidelines, based on how many tires need to be replaced:

Replacing one tire: Purchase a new tire that is identical to the other three on your vehicle — the same brand, size and model. This information can be found on the tire sidewall.

Replacing two tires: The easiest choice is to purchase two new tires that are identical to the others on your vehicle, unless you’re dissatisfied with their performance. If that’s the case, it’s OK to switch brands, but stick with the same size and speed rating as your two older tires. The new tires should always go on the rear of your vehicle to minimize the possibility of rear-end skidding in wet or snowy conditions.

Replacing three tires: You’re better off buying a new set of four, in the correct size, and starting off fresh. Even if you already have one that’s practically new, you can save the fourth to use as a spare or backup for later.

Replacing four tires: You have the choice of going with what you had before, or switching to another style or brand in the same size.

One other consideration: Some all-wheel and four-wheel drive systems require that all four tires be the exact same circumference for proper operation. This means that you can’t mix new and worn tires on the vehicle — you’ll need four new ones, no matter what. Check your owner’s manual for this information.

No matter how many tires you get, it’s a good idea to have your wheels aligned once the new ones are on. Poorly aligned wheels will make your tires wear out faster and could cause you some problems while driving, such as feeling the car pull to one side or noticing a drop in fuel efficiency.

How to research tires

If you’re happy with the tires you’ve been driving on, you can certainly replace them with the same brand, model and size. This is the simplest strategy, because now you just need to decide where to get them. More on that below.

But maybe you didn’t love the performance of your current tires. Some reasons for your dissatisfaction might include:

  • They wore out too fast
  • The ride was too hard or too soft
  • You experienced poor braking performance
  • They didn’t grip well in wet conditions
  • Cornering performance was lacking

Good news! You have a lot of options to choose from. With some research, you can find tires that will meet your expectations for wear, ride quality braking and overall wet and dry performance.

tire numbers

The first bit of information you’ll need is your current tire size. This can be found on their sidewalls, molded in large letters. It will be in the same format as this sample:

P215/55 R16 93H

P: Indicates a tire for passenger vehicles and light trucks

215: Indicates the width of the tire in millimeters at its widest point (215 mm)

55: Indicates the aspect ratio of the tire (it is 55% as high as it is wide)

R: Indicates a radial tire

16: Indicates the wheel size in inches

93H: Indicates the tire’s load index and speed rating

The easiest way to proceed is to buy new tires that are the same size as the ones you are replacing. If you have any doubt as to the correct tire size, consult your owner’s manual or the tire information label on the driver’s door jamb.

Note: Some vehicles, particularly performance cars, may use different sizes of tires on the front and rear. Be sure to check your owner’s manual.

Types of tires

Based on your usage and climate, a certain type of tire may be better for you. Let’s look at the different types:

All-season tires: Most vehicles come with this type. It does a decent job in light snow, rain and summer driving. High-performance versions are available if your vehicle or driving style would benefit from them, but be aware that they tend to wear out faster than the standard all-season models.

While all-seasons can be your only set of tires, they won’t be as good in snow as winter tires, or as good during the dry season as summer tires. If your winters aren’t too cold or snowy, and your summers aren’t continuously hot and dry, you can probably use all-season tires year-round without any problems.

Summer or high-performance tires: These are optimized for warm weather and higher acceleration, braking and cornering demands. They aren’t made for intense rain or winter conditions. These tires are best if you live in a climate that is dry and warm, or if you plan to switch to winter tires when it gets cold.

Winter, snow or ice tires: These tires are purpose-built for wintry conditions and cold temperatures. They will stay soft in the cold, can dig into deep snow and can grip icy surfaces that you would be unable to stand up on. They must be removed when it warms up or they’ll wear out rapidly. A good warm-weather option is to switch to summer tires.

All-terrain tires: These are made for occasionally going off the beaten path, as well as driving on paved roads. If you plan to drive on dirt or other irregular surfaces somewhat often, these will give you an extra margin of grip and performance. They’re usually noisier and ride rougher than standard highway tires.

Figuring out which tires to buy

Every manufacturer claims its tires are the best. So how can you objectively pick the best ones for your needs? has done objective performance comparison tests of many tires in various categories. The site also contains customer reviews, which you can search by both the tire model and the vehicles they were mounted on.

You can easily find all the tires available in the size you need, compare prices and warranties, then see how well they actually perform, both in instrumented tests and from people who used them on the same car you drive. You can also buy tires and schedule an installation time in our website here: Shop for tires