A tiresome business

Lewis Hamilton's tyre failure in last Sunday's Turkish Grand Prix was, it appears, caused by 'chunking'. Formula One tyres are a complex and fascinating business. With the addition of this hitherto unreported phenomenon, there are at least three ways in which the performance of an F1 tyre can deteriorate:

• Graining. This is a consequence of the grooves cut into the tyres, by regulation, to reduce the size of the contact patches. Cutting grooves into a tyre creates separate blocks of rubber, and the shoulders of each block are unsupported on one side. Under braking and cornering forces, the blocks of rubber experience a type of leverage, and, under shear forces, the shoulders of each block are ripped away, creating grains of rubber. These grains roll across the surface of the contact patches, reducing the grip of the tyre. The process continues until the blocks of rubber have been eroded to the point where the leverage upon the shorter blocks is insufficient to create any more grains.
  
• Blistering. This occurs when the carcass of the tyre (i.e., the interior of the tyre) overheats, causing patches on the surface to overheat. The rubber peels away at the blister points.
• Chunking. This occurs when small bits of rubber deposited on the track surface (called 'marbles', and not the same as the grains which cause graining), are picked up by a passing tyre, chemically adhere to the tyre, and then harden.

Each of these phenomena are quite separate from the deterioration in tyre performance which takes place due to simple tyre wear!