How to Read Tire Wear

Your car's tires should be checked for wear once a month.

All drivers should check their car tires for wear once a month, as well as before and after long trips. Monitoring tire wear can indicate when the tires should be balanced, aligned, rotated or replaced. If both tire edges are worn, the tires have been under-inflated. Worn center treads indicate over-inflation. Tires with uneven or erratically spaced bald spots and tires that whine or thump indicate the need for alignment, balancing or the replacement of shock absorbers. If your tire wear bar is exposed, your tires have less than 2/32 inch of tread depth and must be replaced.

Things You'll Need

• Tire pressure gauge
• Tire tread depth gauge or American penny and quarter coins

Instructions

1. Place an American penny heads side up into several tread grooves across the tire. If a part of Lincoln's head is always covered by the tread, your tires still have over 2/32 inch of tread depth remaining and are still legal for use in North America.

2. Place an American quarter heads up into several grooves across the tire. If a part of Washington's head is always covered by the tread, your tires have over 4/32 of tread depth remaining.

3. Place an American penny tails up into several tread grooves across the tire. If the top of the Lincoln memorial is always covered by the tread, you have over 6/32 inch of tread depth left on your tire.

4. Measure the tire approximately 15 inches apart around the the center groove of the tire's circumference. Measure the tire similarly around its inner and outer grooves. This will show you if your tire is wearing unevenly.

Tips & Warnings

• Use your tire pressure gauge to determine air pressure in your tires. Inflate or deflate your tires based upon the recommended pressure indicated for your size and brand of tires. Tire pressure should always be measured on a cold tire.

• A tire depth gauge, if you have one, may be used in place of the coins.

• If your tires are wearing unevenly or excessively, take your car in for servicing to correct the problem.

• Do not drive on tires with less than 2/32 inch of tread depth or if your tire wear bars are showing. Such tires are unsafe and illegal to drive on.

References

• Dummies: Checking your Tires For Wear
• Tire Rack:Measuring Tire Tread Depth With a Coin
• Aut Smart fact Sheet: Tire Care and Maintenance