Pirelli P Zero Race SL-R on test: Aero road bike tyres for chasing seconds
Robert Kühnen
· 10.06.2026
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The fact that tyres play a part in the overall system of bicycle aerodynamics is not a completely new insight. Mavic was the first manufacturer to experiment with tyre/wheel systems in order to optimise aero performance. However, the most successful so far has been a co-operation between Swiss Side, Continental and DT Swiss: the Conti Aero 111 showed remarkably good properties in the TOUR wind tunnel test. The special profile prevents the airflow on the front wheel from breaking off - and this 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 changes the tyre shape
Pirelli has now achieved something similar with the new P Zero Race SL-R is achieved. However, the Italians' trick is a little different. Pirelli does not rely on a special profile like Continental, but manipulates the shape of the tyre to make the airflow more compliant. Specifically, Pirelli thickens the tyre just above the rim flange. The tyre merges more steeply into the rim, the sidewalls are almost vertical and - viewed in cross-section - 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.
Our test model is the slimmest version of the tyre and is nominally 28 millimetres wide; on a rim with an inner width of 23 millimetres, it bulges to a width of 30 millimetres; on the 25 mm rim, which is not compatible according to ETRTO regulations, it is even 31 millimetres wide. Above the rim flange, the tyre leaves a gap of 1.8 millimetres.
The lightweight tubeless-ready carcass can be fitted by hand, and with a high-flow reserve fillmore valve, the tyre immediately pops into the rim flange. With the classic Presta/Sclaverand valve, we had to remove the valve core in order to quickly pump enough air into the tyre. In the centre of the tread, the tyre is noticeably flexible and thin thanks to only two carcass plies.
The 277 gram tyre rolls very easily on the bike. It steers agilely, corners well and is very quiet. When riding in gusty winds, the front wheel runs smoothly, but this may also be due to the aerodynamically good-natured Leeze rim. The grip of the tyre is always difficult to judge when riding freely. However, the tyre behaves flawlessly and feels secure at all times during the 1000 kilometres of testing, even on wet roads.
Design from the wind tunnel
The aerodynamics test, which we carried out in the GST wind tunnel in Immenstaad, reveals how much the tyre contributes to the aerodynamics of the wheel. We used our reference bike, the Canyon Ultimate, but also a very fast, as yet unpublished aero road bike. We mount the tyre on different wheels and compare the aero performance with the classic Conti 5000 STR in 28 millimetre width and Conti's Aero 111 in 26 and 29 millimetre width. We choose our pedalling dummy as the set-up to get as close as possible to reality.
Pirelli has not designed the P Zero Race SL-R as a special front tyre, but rather for the front and rear wheels, partly because the rolling resistance has also been optimised. In our experience, however, measurable aerodynamic benefits from the tyre can only be expected on the front wheel. We have therefore limited our aero tests to the front wheel in order to save valuable wind tunnel time.
We tested the tyre on wheels with inner widths of 19 to 25 millimetres and 40 to 60 millimetre high rims. The measurements show that at a racing speed of 45 km/h, in a fast aero road bike and mounted on a fast wheel (DT Swiss ARC 1100 65), Pirelli's 28 mm tyre is almost on a par with Conti's Aero 111 in 29 millimetre width in terms of aerodynamics. Conti's aero tyre is only a tad faster with a very oblique airflow, with a weighted average of 0.5 watts.
Pirelli and Conti almost on a par
On the slightly less streamlined frame of the Canyon Ultimate and on a 50 mm DT Swiss ARC 1100 wheel, the Pirelli tyre performs somewhat less well, placing itself aerodynamically between the Conti 5000 (28 mm) and the Conti Aero 111 (29 mm). However, the average gaps are still small at 1.5 watts each.
The measurements show that at a racing speed of 45 km/h, in a fast aero road bike and mounted on a fast wheel (DT Swiss ARC 1100 65), the aerodynamics of Pirelli's 28 mm tyres are almost on a par with Conti's Aero 111 in 29 millimetre width. Conti's aero tyre is only a tad faster with a very oblique airflow, with a weighted average of 0.5 watts.
On the slightly less streamlined frame of the Canyon Ultimate and on a 50 mm DT Swiss ARC 1100 wheel, the Pirelli tyre performs somewhat less well, placing itself aerodynamically between the Conti 5000 (28 mm) and the Conti Aero 111 (29 mm). However, the average gaps are still small at 1.5 watts each.
On a wide Leeze wheel with 42 millimetre high rims and 25 millimetre inner dimensions, the Pirelli tyre fits very well into the good-natured flow pattern of the rim. There is no flow separation up to 20 degrees of diagonal flow. In terms of handling, this means a safe ride even in gusty winds, proving the aerodynamic effectiveness of the P Zero.
Outstanding smooth running
Let's move on to rolling resistance. As usual, we used our manufacturer-independent measurement method to measure the rolling resistance on two surfaces, a very fast concrete track and a rough track. According to this, the P Zero Race SL-R belongs to the group of the fastest tyres at the level of special time trial tyres. At 35 km/h, we measured a rolling resistance of just 13.2 watts at 5 bar for a system weight of 85 kilograms. In terms of measurement accuracy, this is the level of the Conti TT time trial tyre with a width of 28 millimetres and an excellent 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 an average tyre on perfectly smooth asphalt. Fascinating!
Despite the great smoothness, the tyre offers enough rubber for a normal mileage. The tyre is only 1.9 millimetres thick in the centre, which is very little. Thanks to the very thin carcass with only two plies in the centre, around 1.5 millimetres of this is accounted for by the rubber layer. Over the 1,000 kilometres of the test rides, the rear tyre lost a quarter of its rubber, which indicates a possible mileage of 4,000 kilometres. The rear tyre remained free of cuts. The tyre has no wear indicators that could indicate when it needs to be replaced.
A thin puncture protection layer is integrated, but its effect is only below average. We measured 330 newtons of puncture resistance, which is at the lower end of the spectrum. At the end of the test ride, an unknown object cuts right through the tread of the front tyre. The sealing fluid allows us to continue riding, but a replacement is recommended.
Conclusion
With the P Zero Race SL-R, Pirelli has succeeded in creating an outstandingly fast racing tyre that combines many characteristics: the smooth running is excellent, as with a time trial tyre, the aero performance at high speeds is very good and the ride feel is top. The rubber and puncture protection are adequate for racing, but rather weak for everyday road cycling.
At the start of sales, the tyre is available in 28 and 30 mm widths, with a 32 mm model to follow after the summer. The recommended retail price is 99.99 Euro per tyre. The tyre is manufactured in Bollate near Milan.
