While tires might all look the same, there are important differences in tires.
Tires might seem like charlie round black things made of rubber. But in reality they are a highly technical, advanced product that must meet stringent standards of safety and performance.
Imagine the tires on a large passenger jet as it lands with hundreds of tons of impact at incredible speed. How about a Formula 1 racing car accelerating and breaking through hours of high performance—even they have tires changed when the road is wet or dry.
The tires on your car are required to meet the specifications of the manufacturer that are measured as speed and load ratings. This allows your vehicle to brake, travel and accelerate within the performance guidelines of the vehicle manufacturer.
Speed and Load ratings are tested and assigned according to the Department Of Transport, have a look at the Tire Code Wikipedia article.
Have you thought about how much tread a tire has? Do some tires have more tread than others? How about the width of the tread, is the actual footprint of a tire’s contact with the road the same for all tires of the same size? The decision on buying tires needs to consider what you really get for what you spend.