Blistering happens when bubbles form on the tire surface. Excess heat causes the rubber to separate slightly. These bubbles reduce contact with the track.
Grip drops suddenly when blistering occurs. For example, on a very hot day, tyres may overheat. The surface becomes uneven and slippery. Drivers feel reduced control in corners. Cooling the tyres becomes important. Smooth driving can limit blistering risk. Severe blistering can ruin a stint.