Do you really have to replace all four tires on a Subaru?

Short answer: Not necessarily, but for Subaru’s all-wheel-drive (AWD) models it is usually safest to replace all four tires to avoid drivetrain stress from mismatched tire circumferences.

In practice, you may be able to replace only two tires in some situations if the new tires match the size, brand, and tread depth of the existing ones and are installed on the same axle. When in doubt, consult your Subaru owner’s manual or a dealership service department for model-specific guidance.

How Subaru's all-wheel-drive system works and why tire replacement matters

Most Subaru models use a symmetrical all-wheel-drive layout with a center differential or clutch-based transfer mechanism. This system strives to send torque to all four wheels and maintain balanced traction. If tires have different diameters or tread depths, the wheels can rotate at slightly different speeds, which can force the drivetrain to compensate and potentially introduce uneven wear or stress on the differential and transfer components. Keeping tires with similar circumference is key to preserving AWD stability and long-term reliability.

When replacing all four tires makes the most sense

The following scenarios often lead professionals to recommend replacing all four tires rather than just one or two. The list below helps you gauge when a full replacement is the simplest and most protective option.

• Multiple tires are near the legal tread wear limit (typically around 2/32" or 1.6 mm) or have uneven wear across the set.


• The current tires are a mismatched set in terms of brand, model, or size, which creates diameter differences.


• You are upgrading to a seasonal tire configuration (for example, switching to winter tires) and want uniform performance across all four corners.


• One tire is damaged beyond repair (sidewall puncture, large cut, or separating tread) and you choose to replace the whole set to ensure consistent handling.


• You plan to keep the vehicle long-term and want the simplest maintenance with balanced wear and predictable AWD behavior.

In these cases, replacing all four tires minimizes the risk of uneven torque distribution and helps preserve the AWD system’s reliability and performance.

When you might replace only two tires on an AWD Subaru

There are situations where replacing two tires on an AWD Subaru can be appropriate, provided you follow strict conditions to minimize circumferential differences. The list below outlines typical guidelines for this approach.

• You replace both tires on the same axle (either front or rear) with new tires that are the same size, model, and brand as the existing tires.


• The remaining tires on the opposite axle have tread depths closely matched to the new tires (ideally within a small tolerance, such as a couple of 32nds of an inch).


• The original tires are of the same type (all-season, all-terrain, etc.) and the new tires are not a different profile or diameter.


• After installation, you monitor the vehicle for any unusual handling or noise and consider a tire rotation or alignment check to maintain even wear.

Even when these conditions are met, many Subaru service departments still prefer replacing all four tires to guarantee consistent rolling diameters and to reduce drivetrain load, especially in older or high-mileage vehicles.

What Subaru recommends and practical tips

Because exact guidance can vary by model and year, the safest approach is to consult your specific owner’s manual or a Subaru dealer for your vehicle. In general, Subaru owners and automotive technicians emphasize maintaining similar tire circumferences across all wheels and avoiding large differences in tread depth. If you’re unsure, choosing a four-t tire replacement simplifies maintenance and preserves AWD behavior.

Practical steps to minimize risk regardless of the choice include ensuring tyres are the same size and model whenever possible, keeping tire pressures equal across all four tires, performing timely rotations, and having the alignment checked after any tire change or unusual wear pattern.

Summary

For AWD Subarus, replacing all four tires is the most straightforward way to maintain balanced performance and protect the drivetrain, especially when tires are worn or different from each other. Replacing only two tires can be acceptable under strict conditions (same axle, identical tire specs, and matched wear), but many owners and dealers opt for four tires to avoid potential issues. Always verify model-specific guidance in the owner’s manual or with a Subaru service professional, and prioritize matching circumference and tread depth to keep the AWD system operating smoothly.

Do you have to change all tires on a Subaru if the tire blows?

It. Tires on your Subaru. So one of the things that our competitors. Say is on a Subaru. If you lose one tire doesn't matter you have to buy four tires. So what they're telling you is not true.

Do I need to replace all four tires on a Subaru?

Yes, for most Subarus, you will need to change all four tires at once because its all-wheel-drive (AWD) system requires tires with very similar tread depths to prevent damage to the drivetrain. If the tread depths are not uniform, it can put stress on the differential and other AWD components, which can lead to costly repairs. A tire can only be replaced individually if the tread depth is within about 2/322 / 322/32 of an inch of the other three tires. 
Reasons to replace all four tires on a Subaru

• AWD system requirements: A Subaru's all-wheel-drive system requires all four tires to have a nearly identical rolling circumference to function correctly and prevent damage to the differential. 
• Uniformity and performance: Four new tires will provide the same level of traction, handling, and overall performance, ensuring your vehicle maneuvers and handles predictably, especially in adverse conditions. 
• Preventing costly damage: Mismatched tire diameters can cause the AWD system to bind, leading to vibrations and potential damage to the drivetrain components. 

Exceptions and alternatives

• If the other tires are nearly new: You may be able to replace just one tire if the other three are still very new and have a tread depth of at least 8/328 / 328/32 of an inch. 
• Check the tread depth difference: If you are replacing a tire but the others are not worn out, you can measure the tread depth on the remaining tires. If the new tire's tread depth is within about 2/322 / 322/32 of an inch of the others, you may be able to get away with replacing just the one. 
• Tire shaving: If a new tire cannot be found that matches the tread depth of the remaining three, it is possible to have a new tire "shaved" to match the circumference of your existing tires. 
• Replacing two tires: Replacing two tires on the same axle is sometimes an option, but it is still better to replace all four for Subaru's AWD to prevent potential long-term issues. 

Is the penny test for tires accurate?

The penny test is a reasonably accurate and quick way to determine if your tires have reached the legal minimum tread depth of 2/322 / 322/32 of an inch. If you can see the top of Lincoln's head when you place a penny upside down in the tread, your tires are worn and should be replaced. While useful, it's less precise than using a tread depth gauge, and many safety experts recommend replacing tires when the tread depth reaches 4/324 / 324/32 of an inch for better performance in wet conditions, a threshold that the quarter test can help you assess.
 
How to perform the penny test

1. Find a penny with President Lincoln's head facing you. 
2. Insert the penny into a tire tread groove with Lincoln's head pointing down. 
3. Check if the top of Lincoln's head is visible. 
4. If you can see the top of his head, your tread depth is 2/322 / 322/32 of an inch or less, and your tires need to be replaced. 
5. If his head is completely covered, you have sufficient tread. 
6. Repeat the test in several spots on each tire to check for uneven wear. 

Why the quarter test is recommended as well

• The space between the top of George Washington's head and the edge of a quarter is approximately 4/324 / 324/32 of an inch. 
• Tires with less than 4/324 / 324/32 of an inch of tread have significantly reduced traction, especially in wet conditions. 
• Performing the quarter test is a proactive way to know when your tires are approaching a dangerous level of wear, rather than waiting until they are bald. 

Is it okay to replace only two tires on an AWD?

It is not ideal to replace only two tires on an all-wheel-drive (AWD) vehicle due to the risk of damaging the drivetrain, but it can be acceptable if the tread depth difference is minimal (less than 2/32nds of an inch). If you must replace only two tires, put them on the rear axle and have the older tires moved to the front. If the tread depth difference is greater, you should replace all four tires or have the new tires shaved to match the old ones. 
Why mismatched tires are risky for AWD vehicles

• Drivetrain strain: AWD systems work by compensating for differences in wheel speed. When one axle has new tires and the other has old ones, the new tires' greater circumference can cause constant, unequal speeds between the front and rear axles. This creates excess stress on the center differential and other drivetrain components, which can lead to premature wear or damage. 
• Traction control issues: Mismatched tire sizes can cause the vehicle's traction control and stability systems to work harder and may trigger them to activate more frequently. 
• Safety concerns: A significant difference in tread depth can affect your vehicle's handling, potentially making it harder to control, especially on wet roads. 

What to do if you need to replace only two tires

1. Measure the tread depth: Check the tread depth of the tires you plan to keep. If the difference is more than 2/32nds of an inch between new and old tires, replacing just two can cause damage. 
2. Replace pairs, not singles: If the tread depth difference is significant, replace a pair of tires, not just one. 
3. Install new tires on the rear: Place the two new tires on the rear axle. This is the safer option for handling, as it puts the tires with the deeper tread where they can best prevent hydroplaning and reduces the risk of an oversteer. 
4. Consider shaving the new tire: Some tire shops can shave the new tire's tread to match the height of the existing tires, though this will void its tread-wear warranty. 
5. If in doubt, replace all four: The safest and most recommended option is to replace all four tires at once to ensure consistent tread depth and prevent potential damage to your AWD system.