Many good things in life come in pairs. Socks and mittens, for example, or classic combinations like peanut butter and jelly or milk and cookies. You probably own a pair of earbuds or headphones, and one shoe or one chopstick doesn’t do much good. We can’t replace a single sock or buy only one glove, so why use that philosophy when it comes to our vehicles?

We get it – car maintenance can be expensive. As of early 2026, it costs on average about $900 annually to keep a vehicle in good working condition. We all look for ways to save money, whether it be a sale at our local auto supply shop or a coupon for an oil change. Sometimes, however, the best and safest option is to replace a broken or worn out part in pairs, rather than only springing for one. This may be because the parts have a similar lifespan, so if one goes, the other is probably not far behind. Or it may be the safest option for a stable and balanced drive. Here are four car parts that most experts recommend you replace in pairs.

You settle into your car one evening, ready to go home after a long day or heading out for a night of adventure with some friends. Then you notice the road is dark on one side — you have a burned out headlight. Driving with only one headlight is not only dangerous, it can lead to an expensive ticket. It’s illegal in all 50 states, though the severity of the fine varies. Even a fix-it ticket can be a headache, however, so it’s wise to fix the problem as soon as possible.

According to AAA, headlights typically last between 3,000 to 45,000 hours, depending on the type. Replacing a burned out headlight bulb typically isn’t too expensive. AutoZone estimates that it typically costs between $30 and $300 to have it replaced by a professional depending on bulb type and how difficult the installation is. That professional will likely recommend that you replace both at the same time, even if only one bulb has burnt out. Both headlights are likely around the same age, so if one has reached the end of its lifespan, the other is probably not far behind.

You also want to ensure that your headlights are providing steady, consistent light. If one light is brighter than the other, it’s not only distracting to you, but potentially to other drivers as well. Additionally, replacing a headlight bulb in some cars requires that the bumper be removed, so it makes more sense to replace both bulbs at once.

A flat tire not only ruins a road trip or disrupts your day; it’s also a costly repair. Consumer Reports members paid an average of over $200 for a new tire in 2025, plus the cost of installation. The last thing you want to be told when you’re replacing a flat is that you should pony up for two new tires, but unfortunately that’s often the case.

There are a few things to consider before you whip out your credit card. If you have all-wheel drive, check your owner’s manual to see how much tread difference is acceptable. If your tires are older, however, you may have to replace all four. If your car has front- or rear-wheel drive and the tires are relatively new, you may be able to get away with only replacing one. That isn’t the case if the tires are more than 30% worn. You should buy two tires that match what’s already on your vehicle and place those tires on the rear axle.

If you’re not replacing all four tires, remember to get the same brand, size, and type of tire that’s already on your vehicle. You may spend more than you hoped, but safety should always be your priority.

If a wiper blade is leaving streaks on your windshield every time it rains, or making an annoying squeaking sound that sets your teeth on edge, it’s probably time to invest in a new pair. This is one item on our list that is sometimes sold in packs of two, but you may not always bother to replace both at the same time. You should also measure the blades before you buy new ones, as some vehicles use two differently-sized blades, which may require you to purchase two separate packs.

Because both blades have been exposed to the same use and elements, they are likely breaking down at about the same rate, even if only one is cleaning unevenly. You’ll probably find yourself replacing the second blade weeks or months down the line. Also, pairing a new blade with an old blade may result in poor cleaning and impaired or reduced visibility.

To replace your wiper blades, check your owner’s manual to find the correct size, or use the vehicle-specific finders that are often available on websites like AutoZone or at Find My Wipers. You can also try asking a store employee or check to see if there’s a physical catalog available. You may not want to go with the cheapest option available, as those may wear down faster and end up costing more in the end.

We’ll round out the list with one part that may be less obvious than others – oxygen, or O2, sensors. These sensors measure the oxygen content in your car’s exhaust to help maintain a healthy air-to-fuel ratio. Most vehicles have two types of O2 sensors that measure those levels at different points in the exhaust system, typically before (upstream) and after (downstream) the catalytic converter. The number of sensors in a vehicle depends on multiple factors, including the make, model, and engine size.

These sensors may wear out over time, be damaged by moisture or other environmental factors, or suffer from an electrical malfunction. If your O2 sensor or multiple sensors go bad, you can still drive your vehicle, but it’s not recommended and may cause problems down the line. It may not be immediately obvious that you have a bad sensor, but you may notice a decrease in fuel efficiency, a rough idle, or an illuminated check engine light.

Most experts recommend that you replace the sensors in pairs for synchronized operation. For example, if you have two upstream sensors, you should replace both at the same time. The cost will vary depending on your vehicle and whether you do the work yourself or hire a mechanic. If you don’t have the expertise to take care of the replacement yourself, expect to pay between $150 to $600, according to AutoZone.