Tires wear out from use and also age out from time. Both tread depth and age matter for safety, so knowing how to check each helps you replace tires before they become dangerous.
2/32 in
legal minimum tread
~6-10 yr
age replacement window
📊 Quick Comparison
Measure
Action Point
Note
Tread 4/32 in
Start shopping
traction fading in wet
Tread 2/32 in
Replace now
legal minimum
Age ~6 yr
Inspect closely
rubber aging
Age ~10 yr
Replace
regardless of tread
Tread depth limits
Tires are legally worn out at 2/32 of an inch of tread in most places, and built-in wear bars become flush with the tread at that point. Many experts recommend replacing at 4/32 inch, especially for wet or winter driving, since traction drops well before the legal limit.
Penny test: insert a penny with Lincoln's head down; if you see the top of his head, tread is at or below 2/32 and it is time to replace
Quarter test: at Washington's head you are near 4/32, a good time to start shopping
Age matters too
Rubber degrades over time even with plenty of tread. Many manufacturers and safety groups suggest inspecting tires closely after about 6 years and replacing them by around 10 years regardless of tread depth.
You can read the tire's manufacture date from the DOT code on the sidewall; the last four digits give the week and year.
Other replacement triggers
Replace tires that show sidewall cracks or bulges, exposed cords, repeated punctures, or damage that cannot be safely repaired. Uneven wear can also mean a tire is finished early.
Replace in the right combination
On all-wheel-drive vehicles, matching tire circumference matters, so replacing in sets is often recommended. If replacing only two, the new tires usually go on the rear for stability.
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❓ FAQ
How do I check my tread depth?
Use the penny test: insert a penny with Lincoln's head pointing down. If you can see the top of his head, the tread is at or below 2/32 inch and the tire needs replacing.
Do tires expire even with good tread?
Yes. Rubber ages, so many makers recommend inspecting after about 6 years and replacing by around 10 years, even if plenty of tread remains.
Where is the tire's age stamped?
On the sidewall DOT code. The last four digits are the week and year of manufacture, for example 2523 means the 25th week of 2023.
Should I replace all four tires at once?
On all-wheel drive, matching sizes matter, so full sets are often recommended. If buying only two, put the new pair on the rear for stability.
What besides wear means I need new tires?
Sidewall cracks or bulges, exposed cords, unrepairable punctures, or dry rot are all reasons to replace regardless of tread depth.