Tyres are an integral part of your car and should be looked after at all times. There are many things that can go wrong with tyres and it is easy to miss them until it becomes a major issue. The biggest error people tend to make with tyres is not driving them inflated to the correct level. This may be that they are under or over inflated and both can cause damage, excess fuel usage and even affect handing / stopping distances.
Every two weeks you should have a good look round your tyres and check that they are not only inflated correctly but also free from damage and have enough tread left on them. Even if your tyre appears to be inflated correctly you cannot really tell without using a tyre inflation gauge to get an accurate result.
If you notice any bulges, tears or un-even tread wear on your tyre you need to get it inspected immediately to check that it is safe to drive on. If you are unsure at all, then it is advised to remove the wheel from the car and take it in to a tyre fitting garage to check rather than risk driving on it.
The legal limit for tyre tread is 1.6mm in a continuous band in the centre of the tyre but many garages recommend changing them when they get below 3mm.