The experts said a good way to check your tyre tread depth is by taking a 20p coin and placing it between the main grooves of the tyre. Checking the overall condition of a vehicle's tyres shouldn’t only happen once a year when its MOT takes place. Understanding how to check tyre pressure is easy and takes minutes. “Having illegal tyres not only poses a risk to the driver of the vehicle but also to other motorists and pedestrians. Motorists can be fined up to £2,500 per illegal tyre, so for motorists taking a chance with four illegal tyres, they could face a fine of up to £10,000.