Pirelli PAAS: With a new tire cross-section, Pirelli aims to improve the aerodynamics of the overall tire-rim system – regardless of the width of the latter component.
Technology from the automotive sector is now being used by the Italian tire specialist to make racing cyclists faster. The new approach, called the "Pirelli Advanced Aerodynamic System," is based on an often overlooked insight: the best aero rim is of little use if an unfavorable tire shape leads to premature airflow separation.
Special contour for optimal airflow
The challenge lies in the fact that rims of varying widths and internal widths affect the tire's cross-section – depending on these dimensions, the tire will protrude more or less beyond the rim flange. With the PAAS prototype, Pirelli has positioned the widest point of the tire's cross-section at a precisely defined location. This is intended to make the way the airflow behaves independent of the tire-rim interface. This could also mean that achieving optimal aerodynamics no longer requires precisely matching the widths of the tire and rim. Pirelli states that the advantages of the new tire are "measurable across a wide range of rim profiles." The manufacturer claims a reduction in aerodynamic drag of up to 20% compared to the combination of the respective wheel and the familiar Pirelli P Zero Race TLR RS.
Another advantage of PAAS is that progressive tread wear does not affect aerodynamic performance. Normally, the flattening of the tire due to abrasion is quite detrimental in terms of air resistance. The finding of other manufacturers confirms that the gap between the tire and rim has no adverse effect. Therefore, previous attempts by wheel manufacturers to cover this gap with ring-shaped inlays are retrospectively deemed pointless.
How the new technology performs on the road remains to be seen. At least in professional motorsport, where races are increasingly run at average speeds of around 45 km/h, PAAS could offer a small but crucial advantage.
