Tyres and Fuel Economy
Several factors dictate how a vehicle consumes fuel at a given distance. A lot of activities, in and around a vehicle, affect the overall performance and fuel consumption of an automobile. Though we give little attention to tyres and wheels, it may surprise you how tyres and fuel economy impact a car’s efficiency and amount of gas emissions.
While automobiles are specifically designed for use on roads, the wheels and tyres are the all-vital links between vehicles and roads. All the effort in research and manufacture of vehicles would not make any sense if the rubber did not meet the road.
The size of a vehicle’s wheels is one aspect that contributes to the overall efficiency of the car while in motion. The other aspects are tyre tread designs and tyre pressure. They affect the performance of the vehicle through a process known as rolling resistance.
What is the relationship between tyres and fuel economy?
Rolling Resistance
Rolling resistance is the effort an automobile requires to move the tyres at a constant speed over a road surface or pavement. High rolling resistance implies that more energy is required to move the tyres, while low rolling resistance translates to lower energy requirements.
A car uses a significant amount of fuel consumed to overcome rolling resistance. This simply means that high-rolling resistance tyres translate to low efficiency, higher fuel consumption and an eventual poor fuel economy.
Tyre Tread Design
We agreed earlier in this article that tyres are the all-important link between the vehicle and the road. Let us agree further that tyre treads are the actual ambassadors in this mutual relationship. Please note that at any given time, only a small section of the entire tyre surface is in contact with the road. This area of contact is known as the tyre patch.
It is, therefore, the tyre tread design that dictates the amount of traction between the tyre and the road, and the resultant rolling resistance. Worn tyre treads or incorrect application of treads for a given road surface will negatively impact efficiency and fuel economy.
The basic tyre design incorporates four distinct features that work together to deliver the desired results;
- Tread blocks
These are individual raised rubber sections of the tyre surface. They provide contact, grip, and traction for the tyre whilst on the road.
- Ribs
The raised section of the tread design on the tyre is the rib. The collective tread blocks on the tyre make up the tyre ribs.
- Grooves
These are the deep furrows that cut along and across the entire surface of the tyre. They act as waterways that channel water away from the tyre’s surface.
- Sipes
They are the tiny and slender grooves cut into the tread blocks. These enhance tyre traction and also aid in control while the vehicle is moving.
Tyres Tread Patterns
The deliberate design of modern patterns is to achieve efficiency and better fuel economy. The tyre manufacturers’ aim is to have specific tread patterns for every road surface and weather condition.
They work towards tyres that have a low rolling resistance, promote efficiency, and a better fuel economy. The correct tyre tread patterns for different road surfaces or weather conditions is the secret concoction.
Tyre tread patterns are classified into three main categories;
Symmetrical tread patterns
These are the most common tread patterns used for tyres on passenger vehicles. They are referred to as symmetrical because both the inner and outer parts of the treads are symmetrically arranged. This means that the outer tread design mirrors the inner one.
Also, the ribs formed by the tyre treads are continuous all around the tyre surface.
Symmetrical tread patterns offer a smooth driving experience, optimum directional stability, and low-rolling resistance.
Smooth driving allows minimum weight transfer, good grip on the road, and enhances control even at high speeds.
Directional stability prevents the car from swaying while cornering or braking. This ensures the car constantly stays on course amidst the various elements, such as rolling resistance, aquaplaning, and air drag.
Tyres with symmetrical tread patterns are made to fit and spin in any direction without inhibiting performance. That is why they are also known as multi-directional tyres.
All these are deliberate efforts by tyre manufacturers to deliver tyres that significantly contribute to vehicle efficiency and better fuel economy.
Asymmetrical tread patterns
The outer tread pattern is different from the inner pattern. Usually, the outer tread pattern is larger to ensure good handling on dry roads while the inner pattern is for wet road surfaces.
Additionally, the outer tread blocks are rigid enough to provide enhanced lateral stiffness which allows excellent grip while cornering. The inner tread pattern allows for efficient displacement of water between wet road surfaces and the tyre to avoid aquaplaning.
Remember that the correct mounting of asymmetrical tyres is very vital to achieving the desired benefits. Always follow the instructions clearly indicated on the tyre’s sidewall. Again all the tyres should be aligned in the same direction.
Directional tread patterns
These tyres are specially designed to roll in only one direction. The lateral grooves on both halves meet at the middle to form an arrowhead formation on the tyre surface. Efficient water displacement is the ultimate goal here to avoid aquaplaning even at high speeds.
They also offer high traction for effective handling on muddy roads and snow or ice. This is the perfect solution for high-performance vehicles that require a combination of utmost agility and high speeds.
Great attention to correctly aligning the tyres during mounting is paramount in achieving the projected benefits of these tyres. Also care should be exercised in making sure that all the tyres are aligned in the same direction.
In Conclusion
The correct choice of tyres for a specific road surface and different weather conditions is the all-important cog in achieving vehicle efficiency on the road. A wrong choice will mean over-working the vehicle engine to work against the various elements in achieving stability, grip, and desired speeds.
An overworked engine translates to poor efficiency and ultimately a poor fuel economy.