Graining

What it looks like

The tyre surface develops a rough, beaded texture where torn rubber has reattached. To the driver it feels like sudden, inconsistent grip drops, especially on corner exit. To the camera it shows as a darker, scuffed band across the tread^[2].

Why it happens

Graining is a temperature problem. When a tyre is below its working window, the compound is too hard and brittle to deform and grip. Instead of bonding with the track surface, the tread slides micro-distances under load. Each slide tears a tiny strip of rubber, which then re-deposits on the surface as a bead. The beads disrupt the contact patch, costing grip^[1].

Where it appears most

• The front tyres of an understeering car (steering inputs put high slip angles on cold rubber).
• Tracks where ambient and track temperatures stay low (Imola in May, Monaco in cool conditions, Suzuka in autumn).
• The hard compound on most circuits, especially in its first few laps before reaching temperature.
• Wet-to-dry transitions where the track is cool and damp.

How it clears

Graining usually wears off naturally after several laps as the affected rubber layer sheds and the deeper layer comes to temperature. Drivers manage through it by:

• Lifting and coasting less (keeping more energy in the tyre).
• Taking slightly different lines to load the tread evenly.
• Pushing through it on shorter compounds since the cost-of-staying-out is greater than the cost-of-graining-clearing.

Graining vs blistering

The two are often confused but have opposite causes. Graining comes from a tyre being too cold. Blistering comes from a tyre being too hot. Both produce visibly damaged tread but the temperature reading and the driver's mitigation are opposite.