In automobiles, weight transfer (often confused with load transfer) refers to the redistribution of weight supported by each tire during acceleration (both longitudinal and lateral). This includes braking, or deceleration (which can be viewed as acceleration at a negative rate). Weight transfer is a crucial concept in understanding vehicle dynamics. A small variety of cars, the most popular kind of automobile. ... In automobiles, load transfer is the imaginary shifting of weight around a motor vehicle during acceleration (both longitudinal and lateral). ... Firestone tire A tire (U.S. spelling) or tyre (UK spelling) is a roughly toroidal piece of (usually) rubber placed on a wheel to cushion it. ... Acceleration is the time rate of change of velocity, and at any point on a v-t graph, it is given by the gradient of the tangent to that point In physics, acceleration (symbol: a) is defined as the rate of change (or time derivative) of velocity. ... A brake is a device for slowing or stopping the motion of a machine, and to keep it from starting to move. ... Definitions Ackermann steering geometry Camber angle Caster angle Circle of forces Live axle Oversteer Roll center Toe Understeer Unsprung weight Performance Driving Techniques Double declutching Handbrake turn Heel-and-Toe Left-foot braking Opposite lock See also important publications in vehicle dynamics Categories: Stub ...

Weight transfer occurs as the vehicle's center of gravity (CoG) shifts during automotive maneuvers. Acceleration causes the sprung mass to rotate about a geometric axis resulting in relocation of the CoG. Front-back weight transfer is proportional to the ratio of the center of gravity hight to the vehicle's wheelbase, and side to side weight transfer (summed over front and rear) is proportional to the ratio of the center of gravity hight to the vehicle's track. Liquids such as fuel readily flow within their containers also causing changes in the vehicle's CoG. Furthermore, as fuel is consumed not only does the position of the CoG change, but the total weight of the vehicle is also reduced. In physics, the center of gravity (CoG) of an object is the average location of its weight. ...

By way of example, when a car accelerates, a weight transfer toward the rear wheels is said to occur. An outside observer can witness this as the car visibly leans to the back, or "squats". Conversely, under braking, weight transfer toward the front of the car will occur. Under hard braking it is clearly visible even from inside the car as the nose "dives" toward the ground. Similarly, during changes in direction (lateral acceleration), weight transfer to the outside of the direction of the turn occurs. Possible meanings: In general, an observer is any system which receives information from an object. ...

Weight transfer causes the available traction at all four wheels to vary as the car brakes, accelerates, or turns. For example, because of the forward weight transfer under braking, the front wheels do most of the braking. This bias to one pair of tires doing more `work' than the other pair results in a net loss of total available traction. The net loss can be attributed to the phenomenon known as tire load sensitivity.

An exception is during positive acceleration when the engine power is driving two or fewer wheels. In this situation where all the tires are not being utilized weight transfer can be advantageous. As such, the most powerful cars are never front wheel drive, as the acceleration itself causes the front wheels' traction to decrease. This is why sports cars always have either rear wheel drive or all wheel drive (and in the all wheel drive case, the power tends to be biased toward the rear wheels under normal conditions). Front wheel drive is the most common form of engine/transmission layout used in modern automobiles, where the engine drives the front wheels. ... Rear wheel drive was a common form of engine/transmission layout used in automobiles throughout the 20th century. ... Four wheel drive or 4x4, is a type of four wheeled vehicle drivetrain configuration that enables all four wheels to receive power from the engine simultaneously in order to provide maximum traction. ...

If (lateral) weight transfer reaches the tire loading on one end of a vehicle, the inside wheel on that end will lift, causing a change in handling characteristic. If it reaches half the weight of the vehicle it will start to roll over. Some large trucks will roll over before skidding, while passenger vehicles and small trucks usually roll over only when they leave the road. Fitting racing tires to a tall or narrow vehicle and then driving it hard may lead to rollover.

See also

• Car handling

A cars handling is a description of the way the car performs, particularly during cornering. ...

External links

• DOT rollover ratings by vehicle type