How to Check Tire Tread Depth
Use the penny test or a tread depth gauge to know when your tires are dangerously worn and must be replaced.
Reviewed by Faisal Mohammad
Licensed Automotive Service Technician · 22 years' experience
Key Takeaways
- ▸Penny test: insert a penny head-down — if you see the top of Lincoln's head, the tire is under 2/32" and must be replaced.
- ▸A tread depth gauge gives a precise reading and lets you track wear over time.
- ▸Replace earlier for safety: around 4/32" for rain and 5/32" for winter.
- ▸Uneven wear across a tire signals an alignment, inflation, or suspension problem to fix first.
You can check tire tread depth using the "penny test" or a dedicated tread depth gauge. For the penny test, insert a penny into the tread groove with the figure's head pointing down. If you can see the top of Lincoln's head, your tread is dangerously low — less than 2/32 of an inch — and the tire must be replaced. A tread depth gauge gives you a precise measurement and is the more accurate option if you want to track wear over time.
Tread depth is what channels water out from under the tire so it can grip the road. As tread wears down, your tires lose their ability to evacuate water, dramatically increasing the risk of hydroplaning in the rain and lengthening stopping distances. In winter conditions the effect is even more pronounced, which is why many drivers replace winter tires before they reach the legal minimum.
Check tread in several spots across each tire and on all four tires, because uneven wear is a warning sign in itself. If one edge or the centre is wearing faster than the rest, it usually points to an alignment, inflation, or suspension problem that should be diagnosed before you install a fresh set — otherwise the new tires will wear out the same way.
Step-by-Step Guide
- 1Penny test: insert a penny head-down into the groove — if you see the top of the head, replace the tire (under 2/32 inch).
- 2Use a tread depth gauge for a precise reading and to track wear over time.
- 3Check tread in multiple spots across each tire, not just one.
- 4Check all four tires — uneven wear between them is a red flag.
- 5Consider replacing at 4/32 inch for rain and 5/32 inch for winter, well before the legal minimum.
- 6Edge or centre wear points to alignment or inflation problems — fix the cause before buying new tires.
- 7Have worn tires professionally inspected to rule out suspension issues.
Benefits of Proper Maintenance
- Avoid hydroplaning in the rain
- Shorter, safer stopping distances
- Catch alignment and inflation problems early
- Know exactly when to budget for new tires
- Stay road-legal and safe in winter
Faisal Mohammad
Licensed Automotive Service Technician · 22 years' experience
Faisal Mohammad is a licensed Automotive Service Technician with 22 years of hands-on experience in the automotive industry. He has built, repaired, and serviced thousands of vehicles across tires, wheels, brakes, suspension, and diagnostics, and reviews the tire and automotive guides published by Limitless Tire for technical accuracy.
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