There will be a few changes for the 2019 tyres
Over the course of the first half of the season, it emerged that there were a few changes in the pipeline for the 2019 tyres. Each year, the compounds and structures change slightly, but in 2019 there’s going to be fewer of them, there will be a bigger performance gap between each compound, and they will be described in a different way: with just a soft, medium and hard compound available at every race. Of course these tyres won’t be the same for each grand prix: the hardest compound available for Silverstone will be very different to the hardest compound available for Monaco, for example.
So, for those wishing to go into a little more technical detail, each compound step will be given its own name or letter to distinguish it. Keeping the example of Silverstone and Monaco, for instance, the hard Silverstone tyre might be compound one whereas the hard Monaco compound might be compound three. The exact details (and colours) are yet to be confirmed, but this is the general principle.