New development should save up to 15 watts: First test of the new aero tyre from Pirelli

The new tyre geometry is designed to increase road speeds through a combination of aerodynamics, smooth running, handling and grip. Pirelli developed the P ZERO Race TLR SL-R for time trials, road races and fast rides. The professionals from the WorldTour teams Alpecin-Premier Tech, Fenix-Premier Tech and Lidl-Trek were also involved in the development of the new tyre. The tyre has already been used as a prototype in various races.

PAAS technology with sail effect

The fact that tyres play a part in the overall system of bicycle aerodynamics is not a completely new insight. Mavic was the first to experiment with tyre-wheel systems in order to optimise aero performance. However, the most successful so far has been a collaboration between Swissside, Continental and DT Swiss: the Conti Aero 111 showed remarkably good properties in the TOUR wind tunnel test. The special profile prevents the airflow from breaking off the front wheel - over a wide speed range from leisure to racing speed. According to our wind tunnel tests, the advantage for the overall system can amount to several watts. In addition, the handling of the tyre improves in gusty winds and the front wheel wobbles less when the aero tyre is fitted.

Pirelli now claims to have achieved something similar with the new P Zero Race SL-R. However, the Italians' trick looks a little different. Pirelli uses a slick tyre and manipulates the shape of the tyre to make the airflow more compliant. Specifically, Pirelli thickens the tyre just above the rim flange. The tyre thus merges more steeply into the rim, the sidewalls are almost vertical and do not take on a pear shape. Pirelli calls this patented feature "PAAS", which stands for Pirelli Advanced Aero System. It was developed in a virtual wind tunnel and tested in four (!) physical wind tunnels. The flow management system is designed to work with different rim shapes and widths.

LiteCORE carcass with less rolling resistance

The technology should not impair other properties. Smooth running, ride comfort and road grip should remain at a high level. The new carcass called LiteCORE should even reduce rolling resistance by a further 10 per cent compared to the most powerful Pirelli model. The tyre uses the same rubber compound that is already used in the P-Zero RS model. Mathieu van der Poel won the Milan-Sanremo 2025 and Paris-Roubaix 2025 classics with Alpecin-Premier Tech on this rubber compound.

First driving impression and measured values: As fast as a TT tyre

Our test model is the slimmest version of the tyre and has a nominal width of 28 millimetres, but measures 30 millimetres on a rim with an inner width of 23 millimetres; on the 25 mm rim, which is illegal according to ETRTO regulations, it is even 31 millimetres. Above the rim flange, the tyre leaves a gap of 1.8 millimetres. Both of our test rims are slightly wider than the tyre at its widest point. The tyre fits perfectly on a 51 millimetre high Bontrager Aeolus rim, which measures 31 millimetres at its widest point.

The lightweight tubeless-ready carcass can be fitted by hand, and with a high-flow reserve fillmore valve the tyre jumps straight into the rim flange; with the classic Presta/Sclaverand valve we had to remove the valve core.

The 277 gram tyre feels very light when rolling. Turn-in behaviour is agile, cornering is smooth and the noise level is low. During the test rides in gusty winds, the front wheel runs smoothly, which may also be due to the aerodynamically good-natured Leeze rim. We will find out what part the tyre plays in the aerodynamics and what the exact characteristics are during a wind tunnel test in April.

However, we can already demonstrate the first rolling resistance measurements with our manufacturer-independent measurement method on two surfaces, a very fast concrete track and a rough track. According to these results, the P Zero Race SL-R belongs to the group of the fastest tyres on a par with time trial specialists. At 35 km/h, we measured a rolling resistance of just 13.2 watts at 5 bar for a system weight of 85 kg. Within the limits of measurement accuracy, this is on a par with the Conti TT time trial tyre of the same width and an extremely good value. The new Pirelli tyre beats the Conti GP 5000 S all-rounder in terms of rolling resistance and fulfils the promise of being faster than the P Zero RS.

The tyre works particularly effectively on rough surfaces. To put it in perspective: Pirelli's racing pellet rolls more easily on the very rough test track than a forest and meadow tyre on perfectly smooth asphalt.

As always, the subjective impression of the tyre's comfort depends heavily on the air pressure. At four bar, the tyre on a hookless rim with a 25 mm internal dimension still passes too much to the rider, despite the noticeably flexible centre of the tyre. With 3.8/3.6 bar, the riding impression is much silkier (with a system weight of 75 kg).

Availability and sizes

The tyre complies with the latest ETRTO standards and was developed for modern rims with inner widths of 22 to 25 millimetres. Unlike Conti, Pirelli does not design the Pzero Race SL-R as a special front tyre, but offers it universally for use at the front and rear. In our experience, however, aero performance can only be expected at the front. It is also compatible with hookless rims if the specified air pressure values are adhered to. The P ZERO Race TLR SL-R is initially available in 28 and 30 millimetre widths. A 32 millimetre version will follow after the summer. Pirelli produces the tyre in Italy at its Milan-Bollate plant using FSC-certified natural rubber, which accounts for 21 percent of the total weight. The recommended retail price is 99.99 euros per tyre >> available here.