A road, says Daedalus, is quite a clever mechanical invention. It takes the force applied by a driven wheel, and reacts to it by momentary deformation. The resulting reaction of the road on the vehicle drives it along. Fast or heavy vehicles, by the powerful reaction they impose on the road, soon damage it. Their powered wheels do far more damage than the merely passive load of the coasting wheels. Daedalus sees the force of the engine being applied first to the tyre, and only then to the road. The tyre is canted, at least at the bottom, and the angle of cant applies a force to the vehicle.

So Daedalus wonders what would happen if the tyre were made from his 'slow rubber' of last week. At a slow enough speed, nothing would happen, and the vehicle would proceed with normal engine efficiency along the road. But at some well-defined speed, the slow restitution of the rubber would hold the canting effect well beyond the time of contact. The tyre would become very lossy, and most of the car's energy would appear not in acceleration, but as heat in the tyres. (Carbon black is put into tyres specifically to dissipate heat.)

Thus a tyre of a properly compounded slow rubber would act as an automatic speed limit. On the principle 'never do by law what you can do by engineering', Daedalus advocates the sale of 'slow tyres' to prove to the police that a specific car could never have exceeded the speed limit.

But clearly the law would be better served by a 'slow road' with the equivalent property. Any car or lorry, no matter what its tyres, would then feel a dramatic slowing on passing onto such a road surface. The road would be deformed by the driven tyres, and this deformation would be restored too late to power them along. Instead, the road would get hot.

The slow road might need to be replaced at frequent intervals, as it absorbed the power of many roadhogs, but it could still be a sound investment. On roundabouts, junctions and sharp bends, and on motorways (with the exception of overtaking lanes), it would restrict motorists to the speed limit, without requiring any legal action. A driver would notice nothing, except that no amount of throttle could accelerate him above the legal limit on such stretches of road. Daedalus hopes that such stretches will hardly get warm from the few roadhogs who challenge them, and that their deterioration (thermal and mechanical) will be very slight.