Motoring: Understanding tire load and pressure

Vehicle tires are made of natural rubber, synthetic rubber, and other chemical compounds.

Ever wondered what the numerical codes on the sidewalls of the tires represent? Well, are you aware that tires just like other parts of the vehicle have an expiry date? And how do you keep your tires in good shape for longer?

Well, this week on motoring, we focus on the most ignored part of the vehicle, despite being among the most crucial parts of mobility considering that the rubber meets the road...literally.

Tire Load Index

The Tire Load Index is a numerical code that represents the maximum weight a tire can support when properly inflated. It is part of the tire's sidewall markings and is typically found next to the tire's size information.

The load index is a standardised global system established by organisations like the Tire and Rim Association (TRA).

The load index is normally a two- or three-digit number that corresponds to a specific weight capacity in kilograms. The actual weight capacity varies depending on the specific index number. For instance, a tire with a load index of 95 can carry a maximum load of 690 Kgs, while a tire with a load index of 110 can carry 1,060 Kgs.

Load Range

Load Range, on the other hand, is a letter code that indicates the tire's ply rating and its ability to handle different air pressures to support varying loads. Load ranges are most commonly used for light truck tires (SUVs, pickups, etc.) and are often found in the tire's sidewall markings as well.

Load ranges are labeled with letters such as C, D, E, etc. Each letter corresponds to a specific ply rating and air pressure range. The higher the load range letter, the higher the ply rating and the greater the tire's load-carrying capacity.

Tires with higher load ranges can handle heavier loads and can be inflated to higher pressures.

For instance, a tire with a Load Range C can handle more weight and higher pressure than a tire with a Load Range B. This is important for vehicles that might frequently carry heavy loads or tow trailers. However, the actual load-carrying capacity and recommended air pressure for each load range can vary depending on the manufacturer and tire model.

How long do tires last?

Most tire manufacturers suggest replacing them at most six years from the date of manufacturing.

The durability of the vehicle tires greatly depends on the quality or brand of the manufacturer and mostly on the driving conditions of the vehicle. However, according to many vehicle manufacturers, tires should last at least 8,000km in normal driving conditions. This roughly translates to 4-5 years of normal driving.

Dangers of driving on old tires

All tires are made of rubber compound material that wears out with time. We have had incidents of a vehicle having its tire burst mid-journey. In most cases, it's about old tires that blow out or poorly inflated tires making the driver lose control hence risking lives.

The threading on the tires also helps one gauge how reliable they can be. Once the thread wears off, the traction of the vehicle is reduced automatically making it dangerous to break suddenly or even drive in rainy weather.

How to know the age of your tire?

You can determine the age of a tire by examining its Tire Identification Number (TIN), also known as the DOT number. This number is stamped on the sidewall of the tire and contains information about the tire's manufacturing date.

The TIN is a combination of letters and numbers, typically located on one side of the tire near the edge of the rim.

The last four digits of the TIN represent the tire's manufacturing date. The first two digits indicate the week of manufacture, and the last two digits indicate the year. For example, if the last four digits are "3018," it means the tire was manufactured in the 30th week of 2018.

How to keep your tires in good condition

Inflation

Different vehicles have different tire pressure requirements. An under-inflated tire will bear the load of the vehicle and hence wear out faster. On the flip side, an excessively inflated tire will leave the inner of the tires to handle the weight of the vehicle and hence wear unevenly.

Drive moderately

Rough or aggressive drivers always have to change their tires after a while simply because sudden braking and constant turns make the rubber wear out eventually as compared to those who drive moderately. Avoid sudden starts, stops, and sharp turns.

Tire rotation

It is common knowledge that not all four tires bear the same weight of the car. The front ones always tend to wear out faster because of the weight of the engine and gearbox as compared to the rare ones. It is advisable to once in a while rotate the tires to make them wear out evenly.

Balance and Align

Get your tires balanced and aligned as needed, especially after hitting potholes or curbs. Proper wheel balancing reduces vibrations, while wheel alignment ensures your vehicle travels straight and true. Both practices prevent uneven wear.

Avoid Overloading

Follow your vehicle's load capacity recommendations to avoid overloading your tires. Overloading can lead to excessive wear, reduced fuel efficiency, and safety risks.

Lastly, wash your tires. While at it, avoid using harsh chemicals or abrasive tools that can damage the rubber. Keeping your tires clean helps prevent deterioration and maintains their appearance.