CAN CAR TIRES BE FILLED WITH WATER INSTEAD OF AIR?

While tires are usually filled with air, you may come up with a question of whether some alternatives exist. Could they be filled with some other substance, such as water?

Sometimes, when you need to cross difficult terrain, water is a good option to fill your tires. Image credit: Cedrik Wesche via Unsplash, free license

Why are car tires typically filled with air?

Car tires are typically filled with air primarily because air is readily available, cost-effective, and provides several essential benefits for everyday vehicle operation and safety.

Here’s the list of factors that make simple air the preferred choice for filling car tires:

1. Compressibility: Air is highly compressible, which means it can absorb impacts from the road, providing a smoother and more comfortable ride. This compressibility allows the tire to adjust to bumps, potholes, and other irregularities on the road surface, reducing the impact on the vehicle and its occupants.
2. Weight: Air is much lighter than other potential fill materials, such as water. Keeping the weight of the tires low allows to maintain better vehicle efficiency and performance. Lighter tires reduce the overall weight of the vehicle, which in turn improves fuel efficiency and reduces wear and tear on the vehicle’s suspension system.
3. Adjustability: The pressure of air in tires can easily be adjusted according to the load the vehicle is carrying or the driving conditions. Proper inflation according to the vehicle manufacturer’s recommendations leads to optimal tire performance and longevity. Over- or under-inflated tires can lead to uneven tire wear, reduced traction, and increased risk of tire failure.
4. Temperature stability: While air does expand and contract with temperature changes, for standard driving conditions, this characteristic is well understood and can be managed by regularly checking and adjusting tire pressure. The change in volume of air with temperature helps in maintaining adequate pressure within the tires across varying climatic conditions.
5. Safety: Air-filled tires help in maintaining proper contact with the road, providing the necessary traction for safe braking and handling. The ability of air to be compressed and then regain its shape helps to distribute the vehicle’s load dynamically during motion, which aids in stable handling and efficient braking.
6. Cost-effectiveness and availability: Air is freely available and filling tires with it is a low-cost option compared to other gases like nitrogen (which is sometimes used for specific benefits like reduced moisture and more stable pressure changes with temperature variations).

But what about using water instead?

In absolute majority of situations, tires are filled with air. Image credit: Enis Yavuz via Unsplash, free license

Can we use water instead of air to fill tires?

Tires can technically be filled with water instead of air, but this practice is generally not recommended for standard automotive use. Water-filled tires are primarily used in certain agricultural or industrial settings for specific purposes.

So what advantages does water bring in this regard? Here we will explain the main factors making water a better choice in some scenarios and why it’s typically avoided for regular vehicles:

• Agricultural and industrial uses: In certain agricultural settings, such as tractors or heavy machinery, tires may be filled with water to add weight. This extra weight helps increase traction and stability on soft or uneven terrain. The added mass helps the machinery work more effectively, especially when pulling or operating heavy equipment. This practice is known as “water ballasting.”
• Density and weight: Water is significantly denser than air. Filling tires with water instead of air can significantly increase the weight of the vehicle. For regular vehicles, this would lead to reduced fuel efficiency, increased strain on the vehicle’s suspension and drivetrain, and greater wear and tear on the tire itself and the road.
• Handling and performance issues: Water does not compress like air under pressure, which means water-filled tires cannot absorb impacts as effectively as air-filled tires. This leads to a much rougher ride and can adversely affect the handling and braking performance of the vehicle.
• Freezing and corrosion: Water expands when it freezes, which can cause damage to the tire and wheel during colder weather. Additionally, unless specially treated, water can promote corrosion and rust on metal components inside the wheel and valve systems.
• Practicality and safety: For everyday automotive use, water-filled tires would not only be impractical due to the increased weight and reduced compressibility but also unsafe. The inability of water to compress under pressure would result in a loss of the cushioning effect air provides, thereby increasing the risk of tire damage from road debris or potholes.