The ‘20p test’ to evaluate your tyre-tread depth!

A general survey performed in 2017 revealed that around 70% drivers were unaware of the legal minimum tyre tread depth. And yet, tyres determine how well you can maintain control of the car, especially in severe weather conditions when cornering and braking ask for extra grip. In case the tread depth is compromised or below the required rate, the tyres will struggle for stronger grip on the road which increases the chance of accidents.

If you’re still unaware of the tread depth’s importance and considering car tyre replacement anytime sooner, here’s all you should know to avoid the penalty points on the license and checking the tread with a common test we know as ’20p test’.

Significance of the tyre treads

Tyre treads are the grooves or jagged patterns on the rubber surface that are there to dispel water from the road and provide stronger grip to the track. Without tyre treads, the vehicle’s likely to steer out of control especially while cornering and braking on wetter surface since the tread-less tyres are unable to disperse water. A fine example would be of Formula 1 racing cars skimming on wet road with tread-less tyres that would eventually compromise the vehicle’s manoeuvrability, make it spin uncontrollably off the track and worse, smash it into pieces.

The greater the tread depth in the tyres, greater would be their ability to dispel the water from the road surface thus achieving a better grip. It’ll also shorten the stopping distance which is the time it takes your vehicle to stop after application of the brakes. When purchasing a brand new set of tyres from a credible source, they’re likely to come with 8mm tyre tread however with time, tread depth reduces but there’re various contributing factors like driving style, road surface, usual travel distance and more. As the tyre wear down, the genuine 8mm tread would decrease significantly.

So how you can actually drive with a legal tread depth and able to determine the right time for the car tyre replacement! Some of the manufacturers incorporate their tyres with the advanced Tyre Wear Indicators (TWI) that are always visible when the depth drops below the original 8mm. Overtime, the reduction would reach to the point where it’ll coincide with the TWI which is your cue to have the tyres replaced.

The ‘20p test’

Indeed Tyre Wear Indicators are useful, an easier alternative to check the tread depth quickly is performing the ‘20p test’ only if your tyres are missing the TWI. When missing the tyre tread gauge, a 20p coin is all that you need to check the treads by placing the coin in one of the primary tread’s channel and do it multiple time at different points around the tyre. If you can see outer band portion of the coin’s face, it tells the tread’s too shallow, dropped below the legal limit and it’s finally time to replace those rounds as soon as possible.


The ‘20p test’ is a life saver thus keeping you, your vehicle and others on the road safer so if you’re too busy for a proper vehicle detailing, least check the tread depth with a simple coin.

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