Replace both rear tires if one is flat and the other is significantly worn
If your rear tire is flat and you need to replace it, the real question is whether to buy one new tire or two. The answer depends on the tread depth of your other rear tire. If both rear tires have similar tread wear — meaning they are close in age and condition — replace both. If the other rear tire still has substantial tread, you can replace just the flat one, but you need to match the tire size, load rating, and tread pattern as closely as possible.
The reason this matters is traction and handling. Rear tires with mismatched tread depths can cause your vehicle to pull to one side, especially in wet conditions or during hard braking. All-wheel-drive vehicles are more sensitive to this mismatch than front-wheel-drive cars, but it affects any vehicle. A tire shop can measure the tread depth of your good rear tire with a penny test or a tread depth gauge — most shops do this for free when you bring the flat tire in.
If you replace only one rear tire, the new tire will have full tread depth while the other has worn tread. This creates an imbalance. Most tire shops will recommend rotating your tires after the repair to even out the wear, which means moving the new tire to the front and bringing a front tire to the rear. This is a normal step and usually costs between $15 and $50 depending on your location and whether the shop charges separately for rotation.
Key Takeaways
- If both rear tires have similar tread wear, replace both to maintain even traction and handling.
- If the other rear tire has substantial tread remaining, you can replace just the flat one, but the new tire should match the size, load rating, and tread pattern of the worn tire.
- A tire shop can measure tread depth for free using a penny test or gauge to help you decide whether one or two tires are needed.
- After replacing one rear tire, ask the shop to rotate your tires so the new tire moves to the front and wear becomes more balanced.
- All-wheel-drive vehicles are more sensitive to tread depth mismatches than front-wheel-drive vehicles, so replacing both rear tires is safer on AWD cars.
How to measure tread depth on your other rear tire
The penny test is the quickest way to check tread depth yourself before you go to a tire shop. Take a penny and insert it into the tread groove with Lincoln's head upside down and facing you. If the top of Lincoln's head disappears into the tread, you have at least 2/32 of an inch of tread remaining. If you can see the top of his head, the tread is below 2/32 of an inch and the tire should be replaced.
The legal minimum tread depth in most U.S. states is 2/32 of an inch, but safety experts recommend replacing tires at 4/32 of an inch, especially if you drive in wet conditions. A tire shop can measure the exact depth with a tread depth gauge, which gives a precise number rather than a pass-or-fail result. If your other rear tire reads 4/32 or higher, replacing just the flat tire is reasonable. If it reads below 4/32, replacing both is the safer choice.
Matching tire specifications when replacing one rear tire
If you decide to replace only the flat tire, the new tire must match the specifications of the tire you are keeping. These specifications are printed on the sidewall of your tire and also listed in your vehicle's owner manual or on a sticker inside the driver's door jamb. The key numbers are the tire size (for example, 225/65R17) and the load index and speed rating (for example, 95H).
The tread pattern should also match as closely as possible. This means the grooves and sipes — the small cuts in the rubber — should be similar between the old and new tire. If you buy a tire with a different tread pattern, the two rear tires will wear at different rates and handle differently in wet or snowy conditions. Most tire shops will help you find a tire that matches your existing tire, or they can recommend a comparable model from the same manufacturer or a competitor.
Avoid mixing tire brands or types on the same axle if you can help it. If your other rear tire is a summer tire, buy a summer tire for the replacement. If it is an all-season or winter tire, match that type. Mixing types can affect how your vehicle handles and how quickly each tire wears.
Cost difference between replacing one tire and two
The cost of a single tire varies widely depending on the size, brand, and quality level. A budget all-season tire for a sedan might cost $80 to $150, while a premium tire for the same vehicle could cost $200 to $400. A high-performance or all-terrain tire for a truck or SUV can cost $150 to $500 or more per tire. Replacing two tires doubles this cost, but you avoid the expense of a tire rotation and the risk of uneven wear later.
When you get a quote from a tire shop, ask whether the price includes mounting, balancing, and disposal of the old tire. These services typically add $15 to $50 per tire. If you are replacing only one tire, also ask about the cost of a tire rotation, since that is the recommended next step. In some cases, the total cost of replacing one tire plus rotation is close to the cost of replacing two tires without rotation, so it is worth comparing the full bill.
All-wheel-drive vehicles and tire replacement
If your vehicle has all-wheel drive, replacing both rear tires is more important than it is for front-wheel-drive or rear-wheel-drive vehicles. All-wheel-drive systems distribute power to all four wheels, and they rely on all four tires having similar tread depth and rolling diameter. When one tire has significantly less tread than the others, the all-wheel-drive system can sense the difference and may engage the center or rear differential in ways that cause jerking, pulling, or premature wear on the drivetrain.
Some all-wheel-drive vehicles have a tolerance of about 2/32 of an inch difference in tread depth before the system is affected. Others are more sensitive. If you own an all-wheel-drive vehicle and your other rear tire is worn, replacing both rear tires is the safest choice. Check your owner's manual for your vehicle's specific tire replacement recommendations, as some manufacturers require all four tires to be replaced together if one is damaged.
When to replace all four tires instead
In some situations, replacing all four tires makes sense even if only one is flat. If all four tires are the same age and have similar wear, replacing just one creates an imbalance that will require frequent rotations to manage. If your tires are more than five years old, the rubber begins to degrade regardless of tread depth, and replacing all four ensures consistent performance and safety.
If you are planning to keep your vehicle for several more years and your other three tires are in good condition, replacing one or two tires is reasonable. If you are selling the vehicle soon or if the other tires are nearing the end of their service life, replacing all four tires may be more cost-effective in the long run because you avoid multiple repair visits and the hassle of managing mismatched tires.
Frequently Asked Questions
Can I drive on a flat rear tire to get to a tire shop?
No. Driving on a flat tire, even for a short distance, damages the sidewall and internal structure of the tire beyond repair. It also damages the wheel rim. Pull over safely, turn on your hazard lights, and call for roadside information or use a spare tire if your vehicle has one. Driving on a flat tire can cost you a new wheel in addition to a new tire.
What if I only have a temporary spare tire?
A temporary spare, also called a donut, is designed for short-term use only — typically up to 50 miles at speeds under 50 mph. Use it to reach a tire shop, but do not drive long distances or on highways. Once you reach the shop, you can decide whether to replace one or two tires based on the condition of your other rear tire. Do not leave the temporary spare on your vehicle permanently.
Is it okay to replace just the front two tires and leave the rear tires as they are?
No. Tires should be replaced in pairs on the same axle — either both front or both rear. Replacing tires on different axles creates handling problems. If your flat rear tire needs replacement, focus on the rear axle. If your front tires are also worn, address them separately or plan to replace all four at once if they are similar in age.
How long does a tire replacement take at a shop?
Replacing one or two tires typically takes 30 minutes to an hour, depending on how busy the shop is and whether the tires are in stock. If the shop needs to order your tire, the wait could be several days. Call ahead to confirm availability and ask about wait times before you bring your vehicle in.
Should I buy the same brand as my other rear tire?
Matching the brand is ideal but not always necessary. Matching the size, load rating, tread pattern, and type (all-season, summer, winter) is more important. If your other rear tire is a common model that is still in production, buying the same brand and model ensures the best match. If that tire is discontinued, a comparable tire from another brand with similar specifications will work.