Tyres are a very important (maybe the most important) component of your car or truck because they represent your only contact between you and the road surface. Drive with bald or faulty tyres and you run the risks of accidents and injuries. In the United Kingdom, the law requires a minimum thread depth of 1.6 mm in the main grooves which are situated in the central three quarters of a tyre. On average, you should replace the tyres every 40.000 km. Irrespective of distance travelled, you should change the tyres if the thread depth is below a safety level, but really you shouldn't need a law to force you to change tyres when it is time, for your life, the life of your passengers who will most likely be your family members, and the life of other road users depend on you doing the right thing.
Many consumers don't know enough about tyres to make an educated purchase. For some, the choice comes down to price and/or availability. Others buy tyres based on appearance or reputation. Educated consumers know to purchase tyres based on safety, quietness, road-holding ability, and wear.
Regardless of tyre choice, it is necessary that consumers understand why tyres are so important. tyres are a vehicle's only contact with the road. Even the brawniest engine, strongest brakes, or most advanced antiskid system, is at the mercy of the tyre's grip on the road. Every move a driver makes with the steering wheel or brake or gas pedal is transmitted to the road through the four notepad-sized contact patches of the tyres.
Since a vehicle doesn't have the ability to change tyres like a person changes shoes, consumers must select a tyre that will work year 'round and in every conceivable driving situation. You wouldn't wear high heels to go hiking, and you wouldn't wear ski boots to dance a ballet. However, consumers often ask their cars' tyres to do many things, and many times a vehicle's tyres aren't suited to the task.
Selecting the right tyres for your driving needs is as important as selecting the right vehicle. tyres that are worn won't be able to displace enough water to prevent hydroplaning. Performance tyres won't be able to get much grip in snow. All-season tyres can't manage the heat creased in high-speed driving. Passenger-car tyres might not be able to carry the heavy load found in a contractor's pickup.
But before consumers can select the right tyre, they have to understand a little tyre technology first.