Wobbly-web wheel

It is flexible for axial loads, perpendicular to the disc plane and also for nutating, wobble of the axle at an angle to the main axis.

A coned disc also becomes stiff against axial loads, as the web is no longer purely perpendicular to the axis of the wheel.

The wobbly web effectively "folds" a coned disc wheel into pleats, making it narrower again, but retaining the axial stiffness.

In architecture, similarly, a 'serpentine wall', is strengthened against sideways forces by corrugation, allowing a thinner, lighter, cheaper structure.

Casting foundries prefer a disc that has a consistent wall thickness, as this makes shrinkage simpler to control.

The Lotus wheel's peculiar shape was arrived at deliberately, by keeping this consistent wall thickness for ease of manufacture, and folding it to achieve the required variation of stiffness across the radius.

A common form in British military practice used a single-thickness disc, displaced sideways in sharp-edged segments and joined by radial webs.

[3] Unlike earlier 'waved' wheels, the Lotus design and its distinctive 'wobbles' was a deliberate feature, even down to the way that the wobbles are deeply indented near the hub and soften outwards to the rim.

Towards the rim, distribution of this same force over a greater circumference and metal cross-section thus required less folding and their profile became a gentle wave.

[3] Lotus team's racing colours at this time were green and yellow, often small patches of each with the bodywork substantially of bare polished aluminium sheet.

This glossy bright yellow colour could be applied easily over the greenish-yellow zinc chromate primer used on the wheels to prevent corrosion.

[14] As the rules for Le Mans were still framed as a "sports car" endurance race, they required the carrying of a spare wheel.

Matching 4-stud rear hubs were flown hurriedly from England, avoiding the incompatibility problem, but the scrutineers now objected that if 6 studs had been required before, 4 must be inadequately strong and still refused to allow the cars to compete.

This was mostly due to the far greater torque of its large V8 engine, but it also avoided this situation re-occurring, as the 30 also carried a single spare wheel.

[16] Later Lotus designs, from the 26 onwards, used spoked wheels, although this was more about the shrinking diameter of racing tyres, especially fronts, rather than brake cooling.

Lotus cars of the 1960s are still popular for historic racing, but these wheels are now no longer acceptable for competition scrutineering, regardless of their apparent condition.