Series of DEKRA tests underlines that correct tire pressure is crucial

In Spite of All Tire Pressure Myths: Do Not Over- or Under-Inflate

Mar 20, 2020

The days are getting longer and the temperatures are rising, which means it will soon be time to switch to summer tires. Once tires have been replaced, the same question arises for every driver: what tire pressure do I set? “There are a variety of myths and half-truths in circulation surrounding this question,” said DEKRA tire expert Christian Koch. “Some drive with a lower pressure for the supposedly better grip, while others increase it by 0.5 bar to reduce rolling resistance and thereby fuel consumption.” New DEKRA tests now lead to a clear recommendation.

Some people knowingly drive with a pressure that is too low or too high
Braking and driving characteristics alter depending on tire pressure
DEKRA experts say even the best tire is a compromise

In collaboration with the Baden-Wuerttemberg Cooperative State University and as part of a bachelor’s thesis, DEKRA tested braking and driving characteristics on a dry road at different tire pressures.

“Several hundred braking maneuvers showed that the lower the pressure is, the shorter the braking distance. However, that is just one side of the coin,” the tire expert pointed out. “Because conversely, our road tests involving slalom courses and evasive maneuvers, for example, showed that lower pressure also leads to a noticeable reduction in steering precision.” The ride becomes spongy. The vehicle is sluggish in responding to steering commands. At higher speeds, it becomes uncontrollable. “Moreover, braking behavior is reversed on wet roads. There, a high pressure yields the shortest braking distances,” said Koch.

Clear recommendation to comply with the manufacturer’s specifications
The results of the series of tests are no surprise to the tire expert: “The requirements that a tire has to meet are very wide-ranging. That is why even the best tire always represents a compromise that must reconcile the various requirements in the best way possible.”

His clear recommendation to vehicle owners and drivers is therefore, “Use the pressure that vehicle and tire manufacturers jointly specify for the respective load condition of the vehicle.” These specifications are generally listed on a sticker on the fuel filler flap or on the B-pillar in the area of the driver’s door. “The compromise works best with the specified tire pressure. As a rule, significant deviations from that have a negative effect due to unbalanced tire behavior.”

Today, most newer vehicles are equipped with a tire pressure monitoring system (TPMS) that also needs to be recalibrated after the changeover to summer tires. “To do so, first set the tires to the corresponding pressure, bearing in mind that the tires must always be cold.”

Those who put their summer tires into storage and fit them themselves should check the condition of the tires in terms of damage and wear before fitting them, and replace them or have them repaired if necessary. Those who have their tires put into storage and fitted by a specialist have it easier here. Such checks will usually have been carried out when the tires were put into storage in the fall.