Which of the following affects tyre grip?

The factors that significantly affect tyre grip include tyre pressure, road surface, and speed. Tyre pressure is critical because insufficient or excessive pressure can lead to reduced contact with the road, diminishing grip. The road surface plays a vital role as well; for example, wet or icy conditions can significantly reduce the friction between the tyres and the road, affecting grip levels. Additionally, the speed at which a vehicle is traveling influences grip; higher speeds can lead to longer stopping distances and reduced control, especially when turning.

The other choices, while they may relate to driving dynamics, do not encompass the key elements that directly impact tyre grip in a comprehensive manner. Steering, acceleration, and braking certainly affect how a vehicle handles but don’t directly determine the frictional forces available through the tyres. Similar reasoning applies to RPM and traction control, which pertain more to vehicle performance rather than the actual grip characteristics influenced by the tyres themselves.