Tire Replacement: When to Replace Tires and How to Choose Replacements
The Short Answer
Replace a tire when its tread is worn to the legal minimum or to the built-in wear indicators, when it has damage that cannot be safely repaired, or when it has reached the age limit recommended by the vehicle or tire manufacturer, even if the tread still looks usable. Any one of these conditions is enough on its own.
A suitable replacement tire must match the size, load index and speed rating specified for your vehicle, or exceed the load and speed ratings. Within those limits, choose the tire type that suits your climate and driving. Those specifications are listed on the tire information placard, usually on the driver's door jamb, and in the owner's manual.
Several things can change this answer. Legal tread limits depend on where you drive. Age recommendations differ between manufacturers. All-wheel-drive vehicles may need all four tires replaced together. Vehicles that came with run-flat or other specialized tires may need the same kind of tire again. No source documents came with this guide, so treat the figures below as commonly cited reference points and confirm them against your local regulations and your vehicle's documentation.
Signs That a Tire Needs Replacing
Worn Tread
Tread depth is the depth of the grooves that channel water away from the contact patch, the part of the tire that touches the road. As tread wears, the tire grips less on wet roads and is more likely to hydroplane, which means riding up on a layer of water.
Most tires have tread wear indicators. These are small raised bars molded into the bottom of the main grooves. When the surrounding tread is worn down level with these bars, the tire has reached its wear limit and should be replaced.
Legal minimum tread depth varies by jurisdiction. In many US states the minimum is 2/32 of an inch. In the UK and across the European Union the minimum for passenger cars is 1.6 mm. The UK rule applies across the central three-quarters of the tread and around the whole circumference. Some regions set higher limits, or separate limits for winter tires. Check the rule where you drive. Some tire safety guidance suggests replacing tires before they reach the legal minimum, often at around 4/32 of an inch, if you drive often in rain or snow. This is a recommendation, not a legal requirement.
Damage
Replace a tire, rather than repair it, if it shows any of the following. A tire technician should make the final decision on whether a repair is possible.
A bulge or bubble in the sidewall, which signals internal structural damage; Cuts, cracks or gouges deep enough to expose the cords or internal belts; A puncture in the sidewall or shoulder, the curved edge between the tread and the sidewall; A puncture in the tread that is too large or too close to an earlier repair to fix within the tire maker's repair limits; Damage from being driven while badly underinflated or flat, which can weaken the sidewall even when nothing shows on the outside
Age
Tire rubber degrades over time even when the tire is rarely driven, as with a spare or a seasonal vehicle. Many vehicle and tire manufacturers advise replacing tires after a set number of years regardless of tread depth. The recommendations differ, and figures between about 6 and 10 years are commonly cited. Look in your owner's manual or the tire maker's guidance for the figure that applies to you.
On tires sold in the US, the manufacture date is the last four digits of the DOT code on the sidewall. The first two digits are the week and the last two are the year. For example, 2321 means the 23rd week of 2021. Other markets may use different markings.
Uneven Wear
Tread that is worn more on one edge, worn in the center, or worn in patches usually points to an underlying problem. Common causes are wrong inflation pressure, poor wheel alignment, or worn suspension parts. If the tire is still above its wear limit it may not need replacing yet, but find and fix the cause first. Otherwise a new tire will wear the same way.
How to Inspect Your Tires
You need a tread depth gauge, which costs little at auto parts stores, plus a tire pressure gauge and good light. Inspect with the vehicle parked on level ground, the engine off and the parking brake set. Check pressure when the tires are cold, before driving or after the vehicle has sat for a few hours.
1) Look up your recommended inflation pressure on the door-jamb placard or in the owner's manual. Do not use the maximum pressure molded on the tire sidewall. 2) Check each tire's pressure, including the spare if it has one. Adjust to the recommended value. 3) Measure tread depth in the main grooves at the inner edge, the center and the outer edge. Repeat at several points around the tire. Write down the lowest reading. 4) Compare the tread with the wear indicator bars. If the tread is level with any bar, plan to replace the tire. 5) Inspect both sidewalls and the tread for bulges, cuts, cracks, exposed cords and embedded objects. Stop driving on a tire that has a bulge or exposed cords. Fit the spare or arrange a tow. 6) Find the DOT date code and work out the tire's age. 7) Note any uneven wear pattern and have alignment and suspension checked if you find one.
Your inspection is complete when you have recorded pressure, minimum tread depth and age for every tire and checked each one for damage. If any tire is at its wear limit, damaged or past the recommended age, it needs replacing.
Choosing a Replacement Tire
Match the Specification First
The tire size marking on the sidewall and on the vehicle placard shows the specification. Take 225/65R17 102H as an example. 225 is the section width in millimeters. 65 is the aspect ratio, meaning the sidewall height as a percentage of the width. R means radial construction. 17 is the wheel diameter in inches. 102 is the load index, a code for the maximum load each tire can carry. H is the speed rating, a code for the maximum sustained speed the tire is rated for.
Size: use the size listed for your vehicle. Some vehicles list different sizes for front and rear, or approved alternatives for different wheel options. Load index: match the original or go higher. Never fit a lower load index than the vehicle requires. Speed rating: match the original or go higher. Some jurisdictions and insurers have rules about fitting a lower speed rating, and a winter tire exception may apply in some places. Special construction: if the vehicle came with run-flat tires, reinforced (XL) tires, or tires made for a particular model, check the manual before switching to a different type. Some vehicles with run-flat tires carry no spare. Powertrain-specific needs: electric and hybrid vehicles are often heavier and may come with tires designed for higher loads or lower rolling resistance. Confirm the load requirement for your exact model.
Choose the Tire Type for Your Conditions
Once the size and ratings are fixed, the main decision is the tire type. The comparison below shows general traits of each category. Individual tire models within a category can differ a great deal, so treat these as tendencies, not measurements. If you compare published test results for specific tires, make sure the tests used the same tire size, the same conditions and the same method.
Tire type | Dry and warm-weather grip | Cold, snow and ice | Typical best fit; Summer or performance | Strongest | Poor; rubber hardens in cold | Warm climates, spirited driving, vehicles fitted with them as standard; All-season | Moderate | Adequate for light cold; limited in heavy snow and ice | Mild climates with occasional cold; All-weather (three-peak mountain snowflake symbol) | Moderate | Better than all-season; meets a recognized severe-snow standard | Year-round use where winters bring regular snow but a second set is impractical; Winter | Weaker in warm conditions; tends to wear faster in heat | Strongest | Seasonal use where winters are cold, snowy or icy, or where winter tires are legally required; All-terrain | Moderate; may be noisier on pavement | Varies by model | Trucks and SUVs that regularly drive on gravel, dirt or light off-road surfaces
To decide, start with your climate. If winters regularly bring snow or ice, choose a dedicated winter set or an all-weather tire carrying the three-peak mountain snowflake symbol. Some regions require winter tires or chains at certain times of year, so check local rules. Where winters are mild, all-season tires are usually the practical default. Summer tires make most sense for warm climates or for drivers who put handling first. A summer-tire driver who faces cold months will also need a second set for winter.
Within a category, the trade-offs are usually between grip, tread life, ride comfort, noise and rolling resistance, which affects fuel use or electric range. In the US, the UTQG rating on the sidewall gives a treadwear grade, a traction grade and a temperature grade. Each manufacturer assigns its own grades, so they are most useful for comparing tires from the same brand. In the EU and UK, the tire label shows ratings for rolling resistance, wet grip and external noise on a shared scale.
Decide How Many to Replace
Replacing all four tires at once keeps grip and handling even. If you replace only two, fit them on the same axle. Tire makers commonly recommend fitting the newer tires on the rear axle to reduce the risk of the rear sliding on wet roads, but follow your vehicle maker's guidance if it says otherwise.
All-wheel-drive and some four-wheel-drive systems can be sensitive to differences in tire diameter between axles, and a mismatch may strain the drivetrain. Some manufacturers specify a maximum tread depth difference, or require all four tires to be replaced together. Check the owner's manual. If only one tire is damaged on a vehicle like this, a tire shop may be able to shave a new tire down to match the others.
Getting the Tires Fitted
Mounting tires on wheels and balancing them requires specialized equipment. Have a qualified tire shop do it. Here is what to expect and what to check.
1) Before buying, confirm the replacement matches the placard size, load index and speed rating. Check that the DOT date shows the tires were made recently. 2) At fitting, the shop should mount and balance each tire. On vehicles with a tire pressure monitoring system (TPMS), the shop should service the valve or sensor and reset or relearn the system if the vehicle requires it. 3) Wheels should be tightened to the vehicle manufacturer's torque specification with a torque wrench, in the correct pattern. Ask whether the lug nuts or bolts should be re-checked after a short distance. Many shops and manufacturers recommend doing so. 4) Ask for an alignment check if the old tires showed uneven wear, or if the vehicle has recently hit a curb or a pothole. 5) Before driving away, confirm that pressures match the placard and that no TPMS warning is showing.
New tires often need a short break-in period before they reach full grip, so drive gently at first. Watch for any vibration, pulling to one side or warning light, and return to the shop if any appears. After that, regular pressure checks and tire rotation at the interval in your owner's manual help the new set wear evenly and last.