Is It Safe to Use Different Size Tires on the Same Axle? Exploring the Risks and Considerations

Running two different size tires on the same axle is generally not recommended. Several factors contribute to why this practice can lead to potential issues, both safety and performance-related. In this article, we will explore the main reasons why it's best to stick with the same tire size on the same axle, as well as addressing some common misconceptions.

Handling and Stability

One of the primary considerations when it comes to running different size tires on the same axle is the impact on handling characteristics. When tire sizes differ, the vehicle's handling behavior can become unpredictable, especially during cornering or emergency maneuvers. This inconsistency can lead to a less stable driving experience, making it more difficult to control the vehicle under various conditions.

Wear and Tear

A mixing of tire sizes can also result in uneven wear. The different tread patterns and rolling diameters can cause uneven pressure distribution on the suspension components. This can result in increased wear and tear on various suspension parts, potentially leading to decreased performance and increased maintenance costs.

Differential Damage

In vehicles equipped with all-wheel drive or four-wheel drive systems, running two different tire sizes can place undue stress on the differential. The differential is responsible for distributing power to the wheels, and using mismatched tire sizes can cause it to overwork, leading to premature failure of drivetrain components. This problem can be exacerbated in situations where the vehicle is being driven hard or off-road, further stressing the differential.

Legal and Safety Issues

Another factor to consider is the legal and safety implications of mixing tire sizes. Some jurisdictions have strict regulations regarding tire sizes on vehicles. Non-compliance with these regulations can result in safety issues and potential legal ramifications. It's important to ensure that your vehicle adheres to the tire size requirements specified by your local laws and vehicle manufacturer.

Manufacturer Recommendations

Vehicle manufacturers typically recommend specific tire sizes for a reason. They consider various factors such as performance, safety, and longevity when specifying tire sizes. Deviating from these recommendations can void your vehicle's warranty and may introduce unforeseen safety concerns. It's always best to consult your vehicle's manual or a tire professional before making any tire size changes.

Myth: Balance and Alignment Are Not Affected

While balance is typically adjusted on individual tires, alignment involves the tire/wheel assemblies being properly aligned with each other. Using tires of different sizes can disrupt this alignment, leading to a pulling effect. This is because the rolling rhythms of the tires will be different, affecting the vehicle's steering and handling. Therefore, it's crucial to ensure that both tire sizes are the same before adjusting your vehicle's alignment.

Impact on Driven Tyres

For driven tires (dual tires on the same axle), running different sizes can create additional stress on the differential. The differential is designed to balance the load between the two driven wheels, and varying tire sizes can cause the wheels to travel different distances, placing uneven stress on the differential and potentially leading to premature wear. While it might not be as significant in the short term, the long-term impact can be substantial.

Conclusion

In summary, it is always best to use the same size tires on the same axle to ensure safety, performance, and vehicle longevity. If you have specific circumstances or needs, consulting a tire professional or mechanic is advisable. Ensuring that your vehicle adheres to the recommended tire sizes can prevent potential issues and help maintain the overall health of your vehicle.