Follow This Simple Coin Test To See If You Need To Replace Your Car Tires

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Tires need maintenance and timely replacement when they exceed their life span. Not replacing the worn out tires can be fatal in many ways. It is very important to keep a check on the depth of your tire tread in order to ensure safe driving. There are numerous ways to check the depth of your tires so you can timely replace them. Coin test also known as penny test in other countries, is the most common way to check the depth of your tires tread.

In UK, Europe and Australia, tire tread is measured in millimeters. In USA, the depth of a tire tread is measured in 32nds of an inch. The new tire tread depth depends on the vehicle. The tire tread depth for new tires is different for heavy weight vehicles, SUV’s and normal vehicles like sedans and hatchbacks. And obviously different for motorbikes as well. But for now, let’s keep the discussion to car tires only.

A 5 rupees coin is the best substitute of tire depth gauge for measuring the remaining tire depth. Before moving on to performing the coin test, lets understand the tire tread depth for new, partially worn and totally worn out tires. Here are some tire tread depths according to the condition of tire. These figures are considered to be international standards. If you ignore the tire tread warning and get caught by the police, there is high chance your car will be impounded, and you fined.

• New Tire → 8 mm (7/32″ or 8/32″ depending on the tire maker)
• Partially worn out tire → 5 mm
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• Worn out tire → 3 mm
• Excessively worn out tire → less than 2 mm

If we talk about traffic laws in UK, Europe and Australia, legally you are supposed to change the tires after 1.8 mm.

Here’s an image of tire with approximately 4 mm tire tread.
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All you need in order to perform a coin test is a 5 rupee coin and a few moments out of your time. Follow the steps below and you will know the exact depth of your car tire’s tread.

  1. Place the tip of 5 rupees coin in any of the horizontal and vertical ribs of your tires. Rib actually refers to the horizontal and vertical cuts in the tread of your tire.
  2. Move the penny to one side of the rib while the base of the moon points towards the tread and scroll down the coin.
  3. If the year inscribed below the moon completely disappears between the tread, your tire is new with almost 8mm of tire tread.
  4. If the year inscribed below the moon does not disappear between the ribs, your tire is partially worn out with the remaining depth of approximately 5 mm.
  5. Now rotate the coin down the tire tread until the base of moon points the tread again.
  6. Notice the grain design pattern below the year, if the design pattern does not completely disappears in the tread, the tire is worn out with the remaining is 3 mm.
  7. Lastly, if only some part of the grain design pattern hides behind the tread, an immediate tire replacement is recommended.

Repeat the above steps for various horizontal and vertical ribs in each of your car tires.

Shaf Younus

I'm an Auto Enthusiast, a Student of Computer Science and above all, Citizen of Pakistan.

  • Sanjay Natarajan

    It will be good if u share the tread depth check for bikes too, considering majority of South asians use bikes than cars.

  • Rizwan Qureshy

    Good info and nicely put. Thanks

  • Haroon Zaka Qureshi

    “All you need in order to perform a coin test is a 5 rupee coin..”

    Old or New one 😀

  • Babar Asghar

    yes old one or new one

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