Take the pressure down

The tyre pressure monitor system might seem like a small fish in the active safety pond, but this simple technology helps take care of what Wheels’ tyre industry sources say is still a common car maintenance oversight. The checking of tyre pressures is a task even the most diligent of drivers can neglect to do regularly and, as our tests illustrate, the impact of under-inflation on steering, handling, braking and safety is significant ( as is the effect on tyre wear).

For normal testing, each tyre was inflated to 33psi cold, which is the pressure recommended on the Mazda’s tyre placard. In the name of science, we systematically dropped the front left tyre to 20psi, then the right rear tyre to 20psi, for a run through the slalom and braking tests.

This was immediately obvious from the driver’s seat, with Ren reporting the under-inflated front brought “heavier steering feel and slower steering response.” Looking at the figures, the slalom time increased by seven percent with the low-pressure front and 14 percent with an under-inflated rear, which might not sound a lot, but consider this: The difference between the quickest and slowest tyre on the slalom was nine percent, meaning you gain as much or more swerve and recover ability by inflating your tyres correctly as you do by buying high-quality tyres in the first place.

The braking distances weren’t unduly affected, but the fact that Ren experienced “lazy feel” through the left pedal and a front-end that “walked around” and “didn’t brake in a straight line” suggested the right pressures play a key part in braking stability, too.