Wear of car and truck tires
By R. David Whitby, Contributing Editor | TLT Worldwide July 2023
Uneven or excessive tire wear can lead to failure and microplastic pollution.
Every time a vehicle accelerates, brakes or turns a corner, the tires wear. Even if this is just a tiny bit of wear, millions of tiny particles are thrown off each tire. It has been estimated that half a million tons of tire particles enter the environment in Europe every year. Some of these particles end up on or beside roads and are washed into the soil or water courses when it rains. Others end up in the air, causing pollution. Some also may end up in people’s lungs and blood. They are contributing to the current problem of increasing amounts of microplastics in the environment. While the volume of these particles is not a major source of environmental pollution, as other pollutants are reduced, the percentage contribution of microplastics becomes more important.
Correctly used tires will show normal progressive wear during their lifetime. However, tires can exhibit uneven or abnormal wear, due to specific conditions of use, and this is likely to shorten their lifetime. Uneven tire wear is caused by incorrect inflation. The edges of underinflated tires will make more contact with the road, leading to higher rates of overall wear. The centers of overinflated tires will experience higher rates of wear, because there will be a higher load on a smaller area of contact with the road. Rapid acceleration, excessive braking or going around corners too fast are all likely to result in higher rates of tire wear. Incorrect alignment of the vehicle’s wheels, particularly those in the front, also is likely to result in higher rates of tire wear.
Some of the causes of uneven or excessive tire wear could lead to a weakening of the tire reinforcing structure, which could result in an eventual failure of the tire. Another sign of higher than normal tire wear is a gradual increase in fuel consumption. Manufacturers of tires put tire wear indicators into the tire tread. These are spaced evenly around the tire into the main grooves in the tread. When they are flush with the level of the tread, the tire must be replaced. New tires on cars have a tread depth of 8 mm, and tires are worn out when the depth is 2 mm or less. A tire tread depth gauge can be used to check the tread. If the tread is not deep enough, the vehicle will lose traction, and braking distances will be longer. Also, the vehicle will be more difficult to control in wet weather, and there is a higher risk of aquaplaning.
Because electric and hybrid vehicles are heavier than gasoline or diesel powered vehicles, it might be assumed that tire wear will be higher. Fortunately, tires for electric vehicles have been made to withstand the increased weights, and manufacturers have improved the rubber compounding, sidewall strength and tread and groove design. Because of this, tires for electric and hybrid vehicles are more expensive than regular tires, while wearing much less slowly and lasting longer. Of course, this depends on the way in which the vehicle is driven, because electric vehicles are able to accelerate faster than conventional vehicles.
Research work is now in progress to develop methods to mitigate the problem of worn tire particles. For example, in 2020, a group of four engineers at Imperial College London completed a master’s degree project to develop a device to collect wear particles directly from tires,
in situ in vehicles. Using electrostatics to collect particles as they are emitted, the device is fitted to the wheel and takes advantage of the various airflows around the spinning wheel. Under controlled conditions in a laboratory, the device can collect 60% of airborne particles, which can be recycled into new tires or other materials. Whether these types of devices can be used in practice has yet to be determined, although tests on vans and buses are now being carried out.
David Whitby is chief executive of Pathmaster Marketing Ltd. in Surrey, England. You can reach him at pathmaster.marketing@yahoo.co.uk.