Tire News & Information

Pneumatic trail: What it is & why it's important for safety

Last updated 10/15/2022 - Originally published 9/24/2020
Written by SimpleTire

Think that tires are just black, round, and made of rubber? There's so much more to tires! Tires are tested and redesigned multiple times before they're released for sale. They maintain traction during wet-weather driving and keep you safe on the freeway while you're traveling at a high speed. There's a great demand put on tires, and when it comes to navigating within traffic, they're the key component to vehicle safety. One important aspect of tire safety that engineers measure is pneumatic trail.

What is Pneumatic Trail?

Pneumatic trail is a measure of how a tire's footprint or contact patch changes as it rolls. Pneumatic trail explains how tires can help you keep your stability and control while you drive. This effect occurs regardless of the steered direction of the tires and can result in a surf-like sensation that occurs when traveling at higher speeds. This force develops and is applied to the length of the contact patch with the rear of the contact patch experiencing the greatest pressure force. This lateral force causes the tire to rotate somewhat, which results in physical force known as self-aligning torque.

This pneumatic trail and self-aligning torque is most easily experienced during a turn. The vehicle will continue traveling in a direction, and the steering realigns itself without requiring the driver to do anything. Basically, this force takes over some of the work involved in getting your vehicle through a turn. While the lateral (sideways) force pushes the vehicle to the outside of the turn, the pneumatic trail will come back toward the center when the vehicle comes out of the turn. Most drivers experience the safety benefits of pneumatic trail daily.

Pneumatic Trail Variables

Tread patterns, tire size, tire construction, vehicle weight, road surfaces, and speed can all affect pneumatic trail. Worn tire tread, improper tire inflation, and tire damage also impact pneumatic trail. The pneumatic trail on some tires may result in a skid and spin (oversteer) or in drifting (understeer). Vehicle design, including weight and suspension type, also affects pneumatic trail.

Tire Maintenance and Pneumatic Trail

When tires are well maintained, they should perform well and keep you safe. Maintenance helps tires remain responsive and capable of cornering and turning. Part of that capability is making sure the pneumatic trail does what it should. Maintenance issues like overinflated or underinflated tires can adversely affect pneumatic trail. The same can be said of driving on worn tires in the rain. To keep your tires in the best shape possible, you should check your tire inflation and tread depth at least every month.

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