Critical at: Monaco, Singapore.
Moderate at: Melbourne, Montreal.
Unknown: Sochi.
Road courses are designed and laid down for racing cars to use. Many use specially selected materials to give them a grippy surface and the tarmac under the drivers is almost always perfectly smooth and clean.
Formula One cars are designed to race on such tracks. Their ground clearance is tiny, suspension very stiff and all tyre testing is carried out on such circuits.
Public roads, on the other hand, are designed and laid down for road cars. The materials are selected for durability and value, and construction crews rarely dig out the spirit level to check every inch is as flat as a pancake.
Road markings are added to tell us where to go.
Tens of thousands of normal vehicles on grubby tyres drive up and down such roads every day, depositing dirt, oil and all manner of pollutants that adhere to the surface.
We don't really notice in our heavy, slow road cars with their soft suspension and cold, super-hard tyres.
But put a high-performance, pure racing machine like an F1 car on such a surface, and it won't be a happy bunny.
The accumulated dirt on the already low-grip surface means the racing slick tyres don't "bite" as well as in road circuits. Braking zones are slightly longer, corners cannot be taken as quickly and it's more difficult to get the power down on the exits.
The bumps and lumps we cruise over without noticing? The F1 car feels every single one of them. They affect the car's balance and some, such as the one between Casino Square and Mirabeau at Monaco, are so severe that drivers have to swerve to avoid them entirely.
And when it rains, a new problem emerges—the road markings. Painted white lines are extremely slippery when wet, so avoiding them becomes a priority.
Pirelli tend to bring softer tyres to street circuits to help offset the problem of low grip, but it never goes away entirely.
