Why Sportscars and Hypercars Adopt Larger Wheels While F1 Racing Cars Can Lap at Quicker Times on Smaller Rims: A Look at the Reasons Behind the Design Choices
Over the past few years, there has been a noticeable trend in the adoption of larger wheels among high-performance vehicles like sportscars and hypercars. This raises the question: why have these vehicles embraced bigger wheels, while F1 racing cars continue to perform at high speeds using 13-inch rims? Is it purely for aesthetic reasons, or are there more practical reasons behind this design choice?
The Role of Tire Suppliers and Safety Regulations
One of the primary reasons for F1 cars using larger 18-inch rims is a combination of tire supplier logistics and safety regulations. Pirelli, a global tire manufacturer known for its performance and low-profile tires, has played a significant role in the trend towards larger rims. Pirelli’s expertise in low-profile tires for road use makes it logical for them to apply similar principles to racing tires, thus driving the choice toward larger rims.
Prior to this shift, F1 was supplied with cross-ply tires by Goodyear, which resulted in smaller front tires and larger rear tires. However, this setup is no longer common. The current configuration mandates the use of 18-inch rims, which, despite being relatively small for the immense power and speed of F1 cars, are driven by the need for greater safety. F1 cars average speeds above 230 mph, necessitating more robust tires.
Evolution of Tire and Safety Standards
The change from 13-inch to 18-inch rims in F1 racing cars is grounded in the envelope of tire sizes allowed by governing bodies, as well as the higher speeds and speeds up to 670 mm (26.4 inches) diameter at 35 psi inflation. These tires are custom-made carbon fiber designs that differ significantly from high-performance sport sedans. Each tire position (front and rear) uses a unique compound, and these tires are hand-made daily.
The use of 13-inch rims in F1 did not affect braking performance due to the implementation of advanced carbon ceramic rotors and braking systems weighing 1600 lbs and even lighter. The 278 mm (10.6 inches) diameter rotors, along with special cooling holes and ducts, ensure efficient heat dissipation. This advanced braking system, actuated by a "brake-by-wire" system, helped maintain exceptional braking performance.
The Challenges Faced by Tire Suppliers
Although F1 cars have now adopted larger rims, tire suppliers still face unique challenges. For instance, Michelin encountered issues in 2005 when high temperatures caused a failure in a left rear tire during the Indy road race. This incident sparked the development of custom tires for supercars like the Bugatti, which can achieve speeds up to 261 mph. These specialized tires, using carbon fibers at higher inflation pressures, are unique for each vehicle and cannot be interchanged, even within the same position on the car.
The complexity and customization of tires used in F1 and high-performance cars underscore the importance of advanced materials and design. The need for robust, high-performance tires that can withstand extreme conditions has driven the continuous innovation in tire technology.
In conclusion, the adoption of larger wheels in sportscars and hypercars is driven by a combination of aesthetics, aerodynamics, and performance, while the continued use of smaller rims in F1 racing cars is rooted in safety and regulatory requirements. As technology continues to advance, we can expect to see further innovation in both tire design and overall vehicle performance.