In its 2025 test of summer tyres, Sportauto not only highlights the advantages of mixed diameter fitments. The motoring publication also compares original equipment and aftermarket tyres, emphasising why the former may not be the best choice – despite being tailor made for a specific vehicle model.
In this case the vehicle is a BMW M4 Coupé (G82) with a 3.0 litre six that delivers 480 hp and six-speed manual gearbox Sportauto evaluates four brands of tyre in the combination of 275/35 R19 at the front and 285/30 R20 at the rear, a setup increasingly common in high-performance sports cars. Testing took place at the Alcarras circuit in Spain, a 2.3-mile track featuring ten left-hand turns and four right-hand turns, provided the ideal setting for evaluating the tyres’ capabilities under extreme loads.
Autosport tester Thiemo Fleck subjected the four tyre brands to the usual range of wet and dry braking, aquaplaning resistance, handling, high-speed stability, and comfort tests. The four tyre models Fleck tested includes the Pirelli P Zero PZ4, which, as denoted by the ‘*’ marking on the sidewall, is an original equipment tyre for the BMW M4. Three aftermarket options joined it – the Continental SportContact 7, Michelin Pilot Sport 4S, and Falken Azenis RS 820.
The Falken tyre is the cheapest of the four, at 910 euros (£764) per set, followed by the SportContact 7, which in these sizes would cost 1,070 euros (£898) for a set of four. The Pirelli OE tyres cost around 1,300 euros (£1,091), leaving Michelin with the dubious distinction of offering the most expensive tyres. A set of Pilot Sport 4S tyres as purchased by Sportauto would set M4 buyers back 1,360 euros (£1,141).
Continental a test winner – rated phenomenal
The Continental SportContact 7 emerged as the clear winner, delivering the highest score across testing on wet and dry roads as well as for environmental qualities. It delivered the shortest braking distances in both wet and dry conditions, stopping from 80 km/h in just 29.1 metres on wet roads, outperforming the next-best Michelin tyre by 1.6 metres. The Continental tyre’s precise steering response, reliable wet handling, and predictable high-speed stability made it the top choice.
Although the Michelin Pilot Sport 4S delivered a slightly faster lap time on the dry track, the SportContact 7 excelled in the dry, earning maximum points for braking from 100 km/h as well as subjective lane change safety, steering response and handling. It also demonstrated the lowest fuel consumption, adding an efficiency advantage to its dynamic credentials. With its “impeccable wet performance and the lowest fuel consumption” the Continental tyre secured “a well-deserved victory on the Alcarras asphalt,” comments Sportauto.
Rated very good
Michelin’s Pilot Sport 4S (PS4S) claimed second place, narrowly missing the top spot due to its less predictable wet handling characteristics. While it offered impressive dry cornering grip and stability, it was prone to sudden grip loss when encountering standing water, requiring more driver caution in extreme conditions. Sportauto’s Thiemo Fleck reports that the Michelin tyre is strong in cornering grip but requires more caution in corners. “It achieves high cornering speeds but can suddenly lose grip at the limit, especially when encountering aquaplaning-inducing puddles.”
In terms of lap times, the Michelin was slightly ahead of the Continental and proved itself one of the best tyres for drivers seeking a balance between daily usability and high-speed performance. The PS4S maintained high cornering speeds but lacked the sharpness and predictability of the SportContact 7, making it more suitable for drivers who prioritise comfort and progressive handling over ultimate track precision.
Rated good
The Falken Azenis RS 820, the most affordable tyre in the test, performed decently on the open road but displayed some limitations on the track. It felt slightly unstable at motorway speeds, while grip levels on the Alcarras circuit varied unpredictably, requiring constant steering corrections.
Sportauto says the Falken tyre “delivers predictable performance with reduced wet grip.” In wet conditions, the Falken lagged behind its competitors, recording a braking distance of 32.8 metres from 80 km/h – 3.7 metres longer than the Continental SportContact 7. However, it proved a solid option for spirited road driving and offered good value for money despite its struggles under extreme loads.
Rated satisfactory
Despite being the official OE tyre for the BMW M2/M3/M4, the Pirelli P Zero PZ4 finished in last place, primarily due to its weak wet braking performance. Thanks to its hard rubber compound, designed for higher wear resistance and longevity, the PZ4 delivered a wet braking distance that was over eight metres longer than the Continental tyre, and it also demonstrated significant deficiencies in wet grip. That said, the Pirelli tyre “impresses with its safety-oriented, forgiving, and composed handling, albeit with pronounced understeer.”
Aftermarket vs OE tyres
Why compare aftermarket tyres with an original equipment product? The reason is simple, explains Sportauto. Original equipment tyres are typically developed alongside the vehicle and are often finalised more than a year before the car’s market launch. They must then be produced unchanged for at least five years, often longer, as per the manufacturer’s specifications.
In contrast, tyre makers update aftermarket tyres regularly and these often feature more modern compounds and constructions. Additionally, replacement tyres are not bound by the stringent wear and rolling resistance requirements of vehicle manufacturers, allowing them to focus more on performance and safety. Therefore, as a vehicle ages, it may be advisable to consider replacement tyres rather than sticking with OE products.
19/20-inch – the ideal combination
As for selecting a 19”/20” mixed fitment, Sportauto notes that there are several technical reasons supporting the mounting wider rear tyres on even larger-diameter wheels.
First, performance-driven vehicles primarily power the rear axle. Second, sports cars aim for a low and centrally balanced centre of gravity. Third, a driven rear axle requires more traction and lateral grip reserves than a front axle, which only needs to steer and brake. To achieve this, a larger contact patch is necessary.
This could be achieved by significantly increasing the tyre’s rolling circumference. However, the tractor-like appearance and the substantially higher rotational resistance would severely compromise both the visual and actual dynamics of the vehicle – making this a non-viable option. Therefore, wider tyres are the solution. While the rotational resistance still increases, it does so to a lesser extent. Moreover, the tyre’s contact patch primarily expands in width, which enhances cornering grip and rear axle stability.
Most vehicles with mixed tyre setups aim to keep the rolling circumference of the front and rear tyres as similar as possible, despite differing tyre dimensions. This is partly for aesthetic reasons and partly to accommodate spare tyre considerations. If a spare or emergency tyre with an incorrect rolling circumference is fitted, the ABS and other control systems may malfunction, which is unacceptable. Conflicts also arise when a vehicle is offered in both rear-wheel-drive and all-wheel-drive configurations.
Matching rolling circumferences despite mixed tyre setups can be achieved in many sports cars by cleverly selecting tyre widths and correspondingly lower tyre profiles at the rear. So why the approximately 2.5cm larger diameter wheels? Well, for a tyre size of 275/35 R19, the calculated sidewall height is around 96 mm. If the rear tyre is to be wider – say, 285/35 R19 for 19-inch wheels – the sidewall height increases to 100 mm. While this alone isn’t technically significant, the rolling circumference increases by more than one per cent, which can disrupt the vehicle’s control systems. Alternatives with even wider tyres are hindered by the resulting understeer tendency and limited space in the rear wheel arch. This brings us, fourthly, to vehicle dynamics: Excessively tall sidewalls on the rear axle can delay lateral force build-up during cornering, resulting in less direct and sporty handling.
