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When to Replace Your Tires

A Complete Tire Buying Guide

Tires are among the most crucial safety features on your car. While a car has thousands of parts, only the tires contact the road.

The TREAD Act passed in 2000, requires all vehicles under 10,000 pounds, bought on or after Sept. 1, 2007, to have a tire pressure monitoring system (TPMS). The systems make cars safer than ever before by alerting drivers when they detect a dangerously under-inflated tire. However, drivers shouldn’t rely solely on their TPMS. The systems won’t alert drivers to hazardous tire wear or damage until the issue causes a leak.

Because tires are a “consumable,” just like brake pads and wiper blades, drivers should check them periodically; experts suggest checking them monthly to ensure they remain in good shape. In addition to regular checks, regular maintenance is also crucial. Getting your tires regularly rotated and aligned will extend their life, but all tires will eventually need to be replaced — even if the car rarely leaves the garage.

In those regular checks, owners should look for reduced tread, uneven wear, and objects embedded in the tire’s tread. While uneven wear can indicate a more serious problem, everyday driving will deteriorate even the most expensive, longest-lasting tires.

Tire markings
Lots of information about your tires can be found simply by looking at the sidewalls. / Photo credit: Ford

Getting to Know Your Tires

No matter how old your car is, take a few minutes to examine its tires each month. Start with the sidewall — the area with the printing — and note the tire’s manufacturer, size, type, and production date.

Here’s what that information can tell you:

Manufacturer

There are dozens of tire manufacturers, many of which work directly with automakers. For instance, certain BMW models have Pirelli P-Zero Run-Flat tires, while the new Corvette arrives from the factory with Michelin All-Season Pilot Sport 4 tires. Automotive manufacturers carefully match tires with each of their vehicles, and in many cases, owners should replace worn tires with a new version of the set the car came with.

Many retailers offer online configurators that provide viable options at different price points. The web-based application takes the guesswork out of choosing a higher-performing tire or moving from an all-season tire to one better suited for rain or snow.

There are also reasons to choose an alternative to the original-equipment tire. Shoppers may be looking for better handling, less road noise, or to save money. If you’re looking for something different in your next set of tires, make sure whatever you choose is appropriate for the vehicle you want to put it on. Not all tires work on all vehicles.

Tire Sidewall Information
Credit: Patrick Olsen

Tire size & rating

Automakers choose tires to enhance a vehicle’s comfort, drivability, and safety. To help consumers and mechanics correctly understand a tire’s attributes, numbers and letters are molded into the tire’s sidewall to identify the tire’s characteristics.

For example, here’s how to interpret a tire that reads M+S 235/55R19 101H, like the one in the photo above:

  • M+S: The tire has a rubber compound that can handle Mud + Snow conditions.
  • 235: The tire is 235 millimeters wide.
  • 55: The tire’s height-to-width ratio. In this case, the height is 55% of the width or 129 mm.
  • R: The tire has radial-ply construction (most tires do).
  • 19: The tire fits on a 19-inch wheel (or rim).
  • 101: The maximum load the tire can handle. 101 means the tire is rated for up to 2,337 pounds.
  • H: The tire’s speed rating. “H” means the tire is rated to travel safely, up to 130 mph (210 km/h), in optimal conditions. In most vehicles, the appropriate rating can be found in the vehicle’s owner’s manual or on the glove box door, driver’s side door jam, or gas tank hatch lid. Choosing tires that match or exceed the vehicle’s load and speed ratings is critical for safe operation. For instance, many family sedans require at least an S rating (112 mph), while a high-performance sports car will need tires rated V (149 mph) or above.
  • There may also be a “P” on some tires before the width number (235 in our example). This stands for “passenger” tire.
Tire Speed Chart
Credit: Patrick Olsen

Your tire’s birthday

In 2000, manufacturers adopted a uniform number coding system to mark a tire’s “birth date.” The code starts with DOT — signifying the tire complies with the U.S. Department of Transportation’s tire safety standards — and ends with four numbers. The first two digits represent the week (from 01 to 52) the tire was made during the year, indicated by the following two digits. All tires should be replaced before they reach 10 years old, even if they never leave the garage because rubber can rot over time. Some manufacturers recommend replacing them after even less time has passed.

Recognize Warning Signs

Regular inspection is key to identifying tire troubles before they become safety issues. Of course, no one can predict a tire blowout caused by road debris, but a worn tire can often be identified and replaced before it fails.

Here’s what to look for:

Closeup of checking tire tread wear using a quarter
Regularly checking your tires’ tread is an essential part of safe driving. / Photo credit: JJ Gouin, Getty Images

Tread wear

Today’s tires come with wear indicator bars running across the tread. When the bars are exposed, you have just 1/16th of an inch of tread left — the absolute minimum for safe driving.

Experts suggest not waiting until the tire tread gets that low. Instead, use the two-coin test: Put a U.S. quarter into the tread upside down, with Washington facing you. If you can’t see the top of his head – i.e., the tread goes past that point – you have plenty left. If you can see the top of his head, it’s time to start shopping for a new tire, though you may have some time left before your tread is too far gone; this is where the second coin comes into play. If you can see George’s head, place a U.S. penny upside down into the tread with Lincoln facing you. If you can see the top of Abe’s head, you must replace the tire now.

Noticeable damage

You could have tire damage if you hear sounds louder than normal road noise (like hitting expansion joints or running over train tracks) or a thumping or clicking that changes with your speed. The same may be true if you feel a vibration in the steering wheel or driver’s seat. Have your tires checked by your mechanic.

Likewise, you need to replace your tires if you notice bulges, blisters, cracks, or cuts on the sidewalls. Sidewall damage is hazardous and can lead to sudden tire failure, leading to costly repairs or even injuries.

Uneven wear

Uneven wear can be subtle but costly if left unchecked. Damaged tires, over- or underinflated tires, or alignment issues caused by worn or broken suspension components can erode your tire’s tread in one area faster than on the rest of the tire. This type of wear will look smooth or tapered, indicating damage caused by uneven tire spread across the road. To properly inspect, you’ll have to get on the ground and look the tire over carefully.

If that’s not your thing, many tire stores provide free inspections. Ask a technician to show you the wear and explain how it might have happened. Not only will you feel more confident in your decision to replace the worn tire, but the information could also help you identify other issues with the car’s suspension.

Shopping for Tires

Consumers used to be limited to finding new tires at a few local outlets. Today, new tires can be purchased at car dealerships, local garages, specialized tire retailers, auto parts stores, major chain stores, warehouse clubs, or directly online. Many online retailers will even work with your mechanic, ship the tires directly to their shop, and arrange for installation.

Some outlets will mount, balance, and install new tires in your driveway using mobile installation vehicles with tire-mounting machines, air compressors, and a balancing station; you’ll have to provide the tires yourself.

How much do new tires cost?

In rare circumstances, a single tire can be replaced, but more often, tires should be replaced in pairs or even all four at once for some all-wheel-drive cars. If you’re not replacing all four, the new tires should go on the rear axle when possible. Costs vary greatly depending on the type of vehicle, the tire manufacturer, the size, and the rating.

Tire pricing varies greatly, ranging from less than $100 for lower-rated, commonly available passenger-car tires to well over $1,000 per tire for exotic sports cars. Size and ratings matter, but even the pricing of two tires of the same size and rating can vary greatly. For instance, a quick online search reveals that a Cosmo MuchoMacho Ultra-High Performance All Season 235/40ZR19 96Y tire costs a little over $110 per tire, whereas a comparable Michelin Pilot Sport 4 S Performance Radial 235/40ZR19 96Y costs about $280 per tire.

Doing plenty of research — including consulting experts — is important before purchasing. New tires are a relatively long-term commitment, so it’s worth a little extra time and consideration before making a final decision.

Car Tires


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