How do I check tire tread depth at home?

The penny test: insert a penny into the tread groove with Lincoln's head pointing down. If you can see all of Lincoln's head, the tread is below 2/32 inch — replace immediately. The quarter test: insert a quarter with Washington's head down. If you see all of Washington's head, tread is at or below 4/32 inch — begin planning replacement. For the most accurate measurement, use an inexpensive tire tread depth gauge (under $10 at auto parts stores), which reads in 32nds of an inch.

How long do tires typically last?

Most all-season tires last 40,000–70,000 miles depending on the tire quality, driving habits, and vehicle alignment. Performance tires last 20,000–40,000 miles. Tires used in a hot climate or driven aggressively wear faster. All tires should be inspected and considered for replacement at 6 years old, and must be replaced by 10 years old regardless of remaining tread depth — as stated by Michelin, Bridgestone, and tire safety experts. Check the DOT code on the sidewall to find your tire's manufacture date.

How do I read a tire's age from the sidewall?

Every tire has a DOT (Department of Transportation) code on the sidewall. The last four digits indicate the manufacture week and year. For example, '1823' means the tire was made in the 18th week of 2023. A tire with '1823' on the sidewall is approximately 3 years old. Tires older than 6 years should be inspected annually; tires older than 10 years should be replaced regardless of appearance.

When Should You Replace Your Tires? — Tread Depth, Age, and Warning Signs

Q: When should you replace your tires?

Replace tires when tread depth reaches 2/32 of an inch — this is the legal minimum in most US states. However, 4/32 inch is the safety threshold at which wet braking distance increases significantly. Most tires include wear bars: small rubber ridges between the tread blocks that become flush with the surface at 2/32 inch. When wear bars are visible, replace tires immediately. Also replace tires every 6–10 years regardless of tread depth — rubber compounds degrade with age even if the tire looks fine.

Replace your tires when the tread depth reaches 2/32 inch (the legal minimum) or 4/32 inch for safer wet-road performance. Also replace tires that are 10 years old regardless of remaining tread — rubber degrades with age. Use the penny test, the quarter test, or a $5 tread gauge for a quick check. Check the DOT code on the sidewall to determine tire age.

Tread Depth Guide

Tread Depth	Status	What to Do
6/32 inch or more	Good	No action needed
5/32 inch	Acceptable	Monitor more frequently
4/32 inch	Caution zone	Plan replacement; wet braking significantly impaired
3/32 inch	Replace soon	Dangerous in rain; schedule replacement this week
2/32 inch	Illegal / replace now	At or below the legal limit in most states
1/32 inch or worn smooth	Emergency	Do not drive; replace immediately

How to Check Tread Depth

The penny test (free):

Insert a penny with Lincoln’s head pointing into the groove
If you see all of Lincoln’s head: below 2/32 inch — replace now
If Lincoln’s head is partially covered: above 2/32 inch — check with quarter test

The quarter test (free):

Insert a quarter with Washington’s head pointing into the groove
If you see all of Washington’s head: below 4/32 inch — plan replacement

Tread depth gauge ($5–$10):

Available at any auto parts store
Measures in 32nds of an inch — most accurate method
Check multiple points across the tire width (uneven wear indicates alignment or suspension issues)

Tire wear bars:

Most tires have wear indicator bars built into the tread grooves
When these bars are flush with the surrounding tread, the tire is at 2/32 inch
Visible wear bars = replace immediately

How to Read Your Tire’s Age

Every tire has a DOT code on the sidewall. Look for “DOT” followed by a series of characters. The last four digits are the age indicator:

DOT Code Ending	Meaning
1823	18th week of 2023 = approximately 3 years old
0420	4th week of 2020 = approximately 6 years old
3215	32nd week of 2015 = approximately 11 years old — replace regardless of tread

Age guidelines from major manufacturers:

6 years: Annual inspection recommended
10 years: Mandatory replacement, regardless of appearance or tread depth

Warning Signs a Tire Needs Immediate Replacement

Visible cords or fabric showing through the rubber
Sidewall bulge or bubble — indicates internal structural failure; blowout risk
Deep cuts or punctures in the sidewall (sidewall damage cannot be repaired)
Vibration or shaking at highway speed that wasn’t there before
Repeated loss of air pressure in the same tire
Cracking or dry rot on the sidewall or between tread blocks

Uneven Wear Patterns and What They Mean

Wear Pattern	Likely Cause
Worn in center	Over-inflated tires
Worn on both edges	Under-inflated tires
Worn on one edge only	Misalignment or camber issue
Cupping or scalloping	Worn shocks/struts; needs suspension inspection
Flat spots	Hard braking or leaving car stationary for extended periods

When you replace tires, also get an alignment check — misalignment will wear new tires prematurely.

For tire pricing, see How Much Are Tires?.

Written by WealthVieu

WealthVieu researches and writes data-driven personal finance guides using primary sources including the IRS, Bureau of Labor Statistics, Federal Reserve, and Census Bureau.

The content on Wealthvieu is for informational purposes only and should not be considered financial, tax, or investment advice. Consult a qualified professional before making financial decisions. Full disclaimer · Editorial policy