There are a number of considerations when buying tyres but lets start with some key considerations.
The first is what size is my tyre? Well this can be found on the tyre's sidewall information and will look something like 205/55 R16.
The next important consideration comes right after the size and is the tyre's 'service description' . It is actually two pieces of information which are the tyre's load and speed ratings. These can also be found on the tyre's sidewall information. and consist of a number and letter that acually relate to industry tables meaning that there is consistancy across all tyre makes.
Now we know the size and service description we now need to look at other considerations.