A TAILORED BLEND
THE DEVELOPMENT OF ALPINA TYRES
Whether engine, transmission or suspension: ALPINA engineers put a remarkable amount of development effort into making sure that every new model offers that unique and superior driving experience. However, only one vehicle component is in direct contact with the road. “The tyres play a major role in shaping the vehicle’s character”, remarks Mario Heinle, Head of Tyre Testing at ALPINA. In time for the launch of the all new BMW ALPINA B8, the experienced engineer provides some insight into the development and testing of tyres at ALPINA and explains what distinguishes the new 21" summer tyres of the Gran Coupé.
Tailor-made
It takes around two and a half years to develop new tyres for a BMW ALPINA model. That is an enormous amount of work for just one specific automobile that is produced in small series. But it is worth the effort in any case: “The tyre is part of the DNA of an ALPINA vehicle. You can dial in the suspension perfectly, but if the tyres do not match the vehicle, you will feel it immediately”, explains Mario Heinle, who has been a member of the ALPINA team since 2013.
The initial design phase involves kinematic models and load capacity calculations; tyre dimensions are assessed and eventually a wheel and tyre combination is defined. The cooperation between the ALPINA development departments is unparalleled. “The development of the wheels, tyres and suspension go hand in hand from the outset. During testing, we work closely together, sharing information and looking at where we can make adjustments to achieve a coherent whole. Some finer details only unfold once all the components interact and as a small development team we have a lot of freedom to act on that”, states Heinle.
But it is not only the ALPINA engineers who worked on the tailored blend for the new ALPINA model: “We always collaborate with a premium tyre manufacturer. In this instance for example, Pirelli was our development partner.”
The tyre manufacturer undertakes the search for the right material mix and develops different constructions with varying materials, material compositions, finishes, etc. “We indicate to our development partner what we want to achieve with the tyre, what criteria need to be met and what weighting we are giving to certain characteristics. The experts from Pirelli then start working on the tyre construction for our test procedures. We test the tyres under real conditions and see where they need to be readjusted. It is an iterative development process. We are in constant dialogue with our development partners.” But just how many different tyres do the ALPINA engineers test on the way until the final result, that everyone is happy with, has been reached? “That varies from development to development. For the B8, we tried out at least 15 to 20 different tyre variants until the tyres were finally given the ALP marking”.
The “ALP” stamp of approval
ALP – these three letters on the tyre wall identify a tyre as a model-specific development for a BMW ALPINA automobile. If a tyre is endowed with this manufacturer code, it has been engineered specifically for a certain model and features the blend of comfort, performance and maximum safety that makes it typically ALPINA. “The ALPINA specification and requirement profile is quite particular, not least because our automobiles can be driven at speeds exceeding 300 km/h. But we have the great advantage that we can focus on a single automobile variant, without having to provide a tyre for different derivatives. This means that the requirements are defined much more precisely: we do not have to make any compromises for a wider spectrum of vehicle weights, suspension and chassis systems and so on”, clarifies the vehicle engineer.
Ultra-high performance vs. comfort
Lest we forget: even a model-specific tyre has to reconcile a number of contradictory properties. “Comfort and performance – those are ultimately the two ends of the spectrum that we operate between. Where the focus should lie is a philosophical question. At ALPINA we are always on the search for an all-rounder, a tyre that allows for relaxed driving at high speeds on the motorway as well as some fun on the handling course or exciting roads. Ultimately, it is not our aim to squeeze out the last hundredth of a second on the race track through a purely performance driven tyre design that will result in significantly impaired comfort. We develop high performance luxury cars for everyday use: the driver should be able to tap into the car’s dynamic capabilities during everyday driving. This is what our tyres are designed for”, explains Heinle.
21" Pirelli P Zero (ALP)*
Considering the development of the summer tyres for the BMW ALPINA B8 in particular, the high-performance drivetrain presented one of the core challenges: “With the Gran Coupé, a torque as high as 800 Nm is transferred to the wheels. The tyre has to fit tightly onto the rim, and a great deal of grip is required. We quickly achieved top-level dry and wet handling performance. Then we put a lot of work into refining the tyre’s high-speed stability – after all, the B8 reaches a top speed of 324 km/h. That requires a tyre that is reliable and precise and therefore conveys a high sense of safety. We also fine-tuned the comfort qualities until the very end of the development process. We made tremendous advancements in acoustic comfort in particular, when we equipped the front axle with the Pirelli Noise Cancelling System – a kind of foam insert that is glued to the inside of the treads and absorbs cavity resonance”, reveals Heinle.
The fact that the ALPINA engineers could achieve the typical ALPINA comfort despite the large wheel size and the correspondingly narrow tyre cross-section is, above all, due to being able to concentrate all efforts on one specific suspension system and wheel / tyre combination. “We do not offer any runflat tyres, because of our narrow cross-sections, a runflat tyre is currently incapable of meeting the ALPINA criteria in terms of comfort”, adds Heinle.
The right tyre pressure
Equally crucial for comfort and handling: the right tyre pressure, especially since it affects the tyre’s footprint and the pressure distribution on the road surface. For the BMW ALPINA B8, there are three recommended tyre pressures – one each for a partially loaded and fully load vehicle with no restriction on speed as well as one comfort tyre pressure that is intended for speeds of up to 250 km/h.** “Because of the maximum speeds that we can achieve with our automobiles, finding the right tyre pressure is always a challenge. When driving at high speeds, large centrifugal forces act on the rotating tyre and we need a correspondingly high tyre pressure to prevent damage to the tyre. At speeds of up to 250 km/h, a lower tyre pressure has a positive effect on comfort – we therefore recommend that our customers adapt the tyre pressure according to the driving profile”, advises the ALPINA tyre expert.
Testing to the limit
To work out the intricacies of the ALPINA tyre alignment, Mario Heinle puts prototypes through their paces on test tracks throughout Europe: “We conduct a lot of testing on the BMW test track in Aschheim near Munich. When the weather is too bad in Germany, we migrate to Miramas in the south of France. For cold climate testing, we travel to Scandinavia. However, we also conduct testing in real road conditions, for which we purposely seek out poor sections of road and examine how the tyres respond in everyday driving situations. We use the closed-off test track to test extreme driving situations, such as abrupt lane changes at maximum speeds or in wet conditions. For me personally, it is always an experience to push an ALPINA model to its dynamic limits and also witness how it is possible to handle a vehicle confidently even in such situations thanks to a harmonious suspension and tyre set-up and the necessary driving experience”.
*EU tyre label = E/B/ 72 dB at the front, E/B / 73 dB at the rear.
**All details refer to the German market. The range of tyres offered and recommended tyre pressures vary from market to market. For country-specific information, please contact your local BMW ALPINA dealership or importer. Subject to change without notice.
Fuel consumption and CO2 emissions*:
BMW ALPINA B8 Gran Coupé: Fuel consumption NEDC correlated combined 11.1 l/100 km / 25.4 mpg, CO2 emissions NEDC correlated combined 254 g/km, Efficiency category F (Germany), fuel consumption WLTP combined 11.9 l/100 km / 23.7 mpg, CO2 emissions combined 270 g/km.
*Stated fuel consumption and CO2 emissions are measured pursuant to EU Regulation 715/2007 in its applicable version. For more information see ALPINA.de/DAT-Hinweis.