Check tire tread with a penny or a tread depth gauge

The simplest way to check tire tread is the penny test: insert a penny into the tread groove with Lincoln's head upside down and pointing into the tire. If you can see the top of Lincoln's head, your tread is worn below 2/32 of an inch — the legal minimum in most states — and the tire needs replacement. This test works because the distance from the edge of a penny to the top of Lincoln's head is exactly 2/32 of an inch.

A tread depth gauge is more precise and costs $5 to $15 at any auto parts store. Press the gauge into the tread groove until the shoulder of the tool rests flat against the tire. Read the depth number where the needle stops. Most tires start with 10/32 to 11/32 of an inch of tread when new. Many safety experts recommend replacing tires at 4/32 of an inch, even though 2/32 is the legal limit, because traction drops noticeably in wet conditions below that point.

Key Takeaways

  • The penny test tells you if tread is below the legal minimum of 2/32 of an inch, but a gauge gives you the exact depth.
  • Check all four tires and the spare if you have access to it, because wear is often uneven across the vehicle.
  • Tires worn unevenly — bald on the edges or center — signal alignment or pressure problems that need fixing before you buy new tires.
  • Most tires last three to five years or 25,000 to 50,000 miles, but age matters: tires older than six years should be inspected by a professional regardless of tread depth.

Where to measure and why uneven wear matters

Measure tread in at least three places on each tire: the center, the inner edge, and the outer edge. Uneven wear tells you something is wrong with the vehicle, not just the tire. If the center is bald but the edges have tread, your tire pressure is too high. If the edges are bald but the center has tread, pressure is too low. If one side is bald, your wheels are out of alignment.

Do not replace the tire and ignore the problem. A tire that wears unevenly will wear out the replacement just as fast. Have a mechanic check your alignment and tire pressure before buying new tires. This costs $50 to $150 but prevents you from replacing tires again in a few months.

Check the sidewalls for cracks, bulges, and age

While you are checking tread, look at the sidewalls — the vertical part of the tire between the tread and the rim. Cracks, cuts, or bulges mean the tire is damaged and unsafe, even if the tread is fine. A bulge means the internal structure is failing and the tire can blow out without warning. Replace any tire with visible sidewall damage when ready.

Check the tire's age by finding the DOT code on the sidewall, a series of numbers and letters that ends with four digits. The last four digits are the week and year the tire was made. For example, 2419 means the 24th week of 2019. Tires older than six years should be inspected by a professional, and tires older than ten years should be replaced regardless of tread depth, because the rubber hardens over time and loses grip.

How to read tire pressure and adjust it

Tire pressure affects both tread wear and safety. Check the pressure when the tires are cold — at least three hours after driving or before you have driven more than a mile. Pressure rises as tires heat up, so a warm-tire reading will be higher than the actual pressure.

Find the correct pressure on a sticker inside the driver's door jamb, not on the tire itself. The number on the tire is the maximum pressure, not the recommended pressure. Use a tire pressure gauge ($5 to $20) to check each tire, including the spare. If pressure is low, add air at a gas station or tire shop. If pressure is high, let air out by pressing the valve stem. Check pressure once a month and before long trips.

When to replace tires before they are legally worn

You do not have to wait until tread reaches 2/32 of an inch to replace tires. Many drivers replace them at 4/32 of an inch because wet traction drops sharply below that point, and hydroplaning risk increases. If you drive in rain or snow regularly, replacing at 4/32 is safer than waiting for the legal minimum.

Tires also wear faster if you drive on rough roads, carry heavy loads regularly, or have poor alignment. If you notice tread wearing faster than expected, have alignment checked before the tires are completely worn. Some tire shops offer free alignment checks and can tell you whether replacement is worth the cost.

What to do with old tires after replacement

When you buy new tires, most shops will dispose of your old tires for a fee, usually $3 to $5 per tire. This fee covers recycling or proper disposal. Some shops include disposal in the price; ask before you buy. Do not leave old tires on the roadside or in a landfill without permission — many areas have laws against it.

If the tires still have usable tread, you can sell them to a used tire shop or online marketplace. Used tires with 4/32 to 6/32 of an inch of tread typically sell for $20 to $50 each, depending on the brand and condition. Take photos of the tread and sidewalls, and be honest about any damage or uneven wear.

Frequently Asked Questions

How often should I check my tire tread?

Check tread at least once a month and before long trips. If you notice uneven wear or drive on rough roads regularly, check every two weeks. Tread can wear quickly in the first few months after alignment problems develop, so catching it early saves money.

Can I use a coin other than a penny for the tread test?

A penny works because the distance to Lincoln's head is exactly 2/32 of an inch. A quarter or dime will not give you an accurate reading. A tread gauge is more reliable than any coin test and costs less than a tank of gas.

What if my tires are wearing out faster than expected?

Fast wear usually means alignment is off, pressure is wrong, or you are carrying extra weight regularly. Have alignment checked first — it costs $50 to $150 and often fixes the problem. Check pressure monthly and adjust to the door jamb number, not the number on the tire.

Do I need to replace all four tires at once?

If only one or two tires are worn, you can replace just those. However, if you have all-wheel drive, replacing only two tires can damage the transmission because the new tires will spin at a different speed than the old ones. Ask your mechanic whether your vehicle requires all four to be replaced together.

What is the difference between all-season and winter tires?

All-season tires work in most conditions but lose grip in snow and ice. Winter tires have softer rubber and deeper treads designed for cold weather. If you live where it snows, winter tires are safer than all-season tires, even if the all-season tread looks fine. Winter tires typically last one to two seasons if used only in winter.