If you notice that your car is not performing as well in wet weather or takes longer to stop when braking, then your tyres may need replacing.

Tyre wear is a gradual process so it can be hard to tell when your tyre needs changing so, if you're not sure whether your car needs new tyres, we recommend looking at the vehicle's tyre tread depth, general condition and pressure, along with monthly car checks.

The tread depth must meet legal requirements and tyres must be inflated according to the vehicle manufacturer's recommendations.

Any signs of bumps, bulges or cuts on the tyre itself could cause a blowout when driving and suggest that you need replacements as soon as possible.

Tread depth must be above the legal minimum of 1.6mm throughout a continuous strip in the centre three-quarters of the tread and around the entire tyre circumference.

A quick way to check your tread depth is with a 20p coin. Insert the coin into the tread grooves at three separate places on your tyre. If you can see the outer rim of the 20p piece, then this could indicate that your tread is close to or below the legal minimum of 1.6mm and you should visit National to have your tyres checked.

Having the correct tyre pressure is very important for many reasons, including:

• Helping your tyres to last longer

• Providing a more smooth, comfortable ride

• Fuel efficiency. Under-inflated tyres can increase fuel consumption by 3%, costing UK drivers £600 million every year

• Protecting the environment by reducing carbon-dioxide emissions

Tyres must be correctly inflated according to the vehicle manufacturer's recommendations in the vehicle handbook.

Over-inflated tyres cause excess wear, shortening tyre life, and can result in an uncomfortable ride; under-inflated tyres result in increased fuel consumption and faster wear of the tread shoulders plus an increased chance of impact damage.

Punctures can be repaired providing that they meet British Standard AU159. When checking over your tyres we will be able to advise you if your tyre falls into this category.

Tyres can only be repaired in the central area of the tyre so you'll need to buy new tyres if the sidewalls are damaged as they are not repairable.