Ask the Mechanic: Do tyres affect fuel consumption?
Hello Paul, lately, my car has been consuming a lot of fuel. A mechanic has checked almost everything apart from the tyres. Does the state of my tyres affect my car’s fuel consumption?
Duncan.
Hello Duncan, the nature and condition of tyres has a direct impact on a car’s fuel consumption:
Tyre size and weight
Larger tyres reduce fuel economy while smaller ones increase fuel economy. Larger tyres require more effort or energy (fuel) to move because they are heavier and have more rolling resistance (effort the vehicle must put into moving a tyre). Smaller tyres are more fuel efficient, especially during start, stop or slow traffic.
However, when driving at higher speeds, say on the highway, larger tyres will cover longer distances. Also, the engine has to work harder (use more fuel) to make a smaller tyres cover the same distance at the same speed as the larger tyres.
For larger tyres to be more fuel efficient, they should have shorter tyre walls to reduce weight, such as those on low profile tyres.
Tyre wear or condition
Tyre condition or wear can reduce your fuel economy significantly. The part of your car tyres in contact with the road is called the tyre patch. When this part wears out, the tyres will most likely slip on the road.
This requires more effort from the car engine to move the tyres forward, leading to more fuel being consumed to cover a particular distance.
Tyre tread design
Tyre tread design or pattern can also affect fuel economy. Tyre treads are the rubber around a tyre which makes contact with the road surface. Tyre treads are designed with blocks, lugs, grooves and wear bars, all of which help with car drivability and handling by ensuring road grip, cornering performance, off roading, elimination of heat and water for safe driving. Tyres with shallower treads have better fuel economy because they create less rolling resistance. Tyres with chunkier and more aggressive tread patterns or blocks such as those used offroad are 30 to 35 percent less fuel economical to drive on.
Tyre inflation
Incorrectly inflated tyres can reduce fuel economy by up to 10 percent while under inflated tyres will bulge the tyre walls. This will not only damage your tyres but also increase the tyre surface as well as rolling resistance. This requires more effort (energy/fuel) from your car engine to move the under inflated tyres.
WHY DOES MY CAR LEAN WHEN TURNING AND DIP WHEN BRAKING?
Hello Paul, my Toyota Noah leans when turning and dips when braking. What could be causing this?
Agnes.
Hello John, hybrid cars use their electric motors during starts, take off and overtaking because the electric motor provides more torque or force needed to instantaneously accelerate the car in the direction where its headed. The benefit of the hybrid motor during acceleration at starts and during overtaking is to improve torque, efficiency and economy.
Hybrid electric vehicles are driven by petrol internal combustion engines and one or two electric motors which draw energy from batteries. Hybrid batteries are charged by regenerative braking and the petrol internal combustion engine. The primary propulsion system of a hybrid car is the petrol driven internal combustion engine. The petrol engine propels the car when driving in slow traffic or regular driving.
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