Some Definitions
Whether you’re a driving enthusiast, a 4x4 fan, a lover of fine cars, or simply a discerning driver, you can all discover new driving experiences. Providing as many people as possible with the enjoyment of controlled, sporty driving in all conditions… This is the mission BFGoodrich sets for itself. The definitions below will give you the essential foundations.
DRIVING GUIDE GLOSSARY
REACTIVITY
This is the speed and extent of the tyre/vehicle response to the driver’s inputs. This response can define the “sportiness” of the tyre.
WEIGHT TRANSFER
FRONT-TO-REAR WEIGHT TRANSFER
This is the shift of weight to the front or rear of the vehicle, depending on whether you are braking or accelerating.
When you accelerate, the front of the vehicle tends to lift while the rear lowers, which is referred to as rearward weight transfer. In this case, the rear axle bears more of the vehicle’s weight.
When you accelerate, the front of the vehicle tends to lift while the rear lowers, which is referred to as rearward weight transfer. In this case, the rear axle bears more of the vehicle’s weight.
When you brake, the front of the vehicle tends to lower while the rear becomes lighter. This is referred to as forward weight transfer. In this case, the front axle bears the full weight of the vehicle.
LATERAL WEIGHT TRANSFER
When the vehicle enters a corner, weight shifts from the wheels on the inside of the turn to the wheels on the outside, due to the centrifugal, or lateral, force acting on the vehicle.
OVERSTEER AND UNDERSTEER
OVERSTEER
Oversteer occurs when the rear axle slides more than the front axle. The car appears to turn more than intended, causing the vehicle to enter the corner too sharply.
UNDERSTEER
Understeer occurs when the front axle slides more than the rear axle. The car seems to continue straight ahead even though the wheels are turned. The vehicle tends to run wide in the corner.
4X4 TRACTION
4x4 traction refers to the grip of the tyres on the road surface. Good traction allows 4x4 tyres to maintain effective grip across all types of terrain: asphalt, gravel, sand, or mud.
SLIP ANGLE
The slip angle is the difference between the direction of the wheel’s path and the direction of the vehicle’s path.
BRAKING TORQUE
A technique commonly used by drag racers and during road tests to improve acceleration from a standing start; it involves applying the brakes while accelerating, increasing engine RPM until the brakes are released.
SLIP
This term describes a loss of traction when cornering or accelerating from a standstill. The tyres slide instead of gripping the road surface.