Degradation

As a stint goes on, the tyres wear and overheat, grip falls away and lap times climb. This fade is called degradation, or deg for short, and it is the clock that strategy runs against. A car on fresh tyres is simply faster than the same car twenty laps later.

Two kinds of deg

Thermal degradation

The tyre overheats and loses grip even though there is tread left; it can sometimes be recovered by backing off and letting the rubber cool.

Wear degradation

The tread physically wears away. This is permanent — once the rubber is gone, it is gone.

How fast a tyre degrades is not fixed — it depends heavily on the conditions. A rough, abrasive surface chews rubber away; a hot track pushes tyres toward thermal deg; and a layout full of long corners loads the tyres for longer. The same compound can be a comfortable one-stop tyre at a cool, smooth circuit and a fragile two-stop tyre at a hot, abrasive one.

Teams measure deg carefully in Friday practice to predict how each compound will fade on Sunday. The result decides how many stops to make and when. A driver who can manage the tyres — being smooth, avoiding wheelspin and lockups, and using techniques like lift-and-coast (easing off before the braking zone to cut temperature) — can stretch a stint several laps longer than a driver who attacks every corner, and those extra laps are pure strategic freedom.