Mercedes’ James Allison tips chassis and aero to trump powertrains in 2026 as tyres become bottleneck

Mercedes technical director James Allison has commented on the 2026 regulations and the challenges he is expecting to encounter as the Brackley outfit enters next year's season. Highlighting that the tyres will still be a bottleneck for performance, he added that dependency on a good powertrain could come second to the chassis and aerodynamics of their car.

Speaking to Nextgen Auto, he first spoke about the power delivery of the new power units. 

"Some things are going to change for the better," he said. "The rather unfortunate formula of very high engine loads at the end of the straight will disappear and we will have much more moderate loads at the end of the straight, which will be beneficial for everyone.

"But other things will evolve in a more delicate direction."

2026 brings a number of substantial changes to the cars, including a powertrain that equally splits its power between the combustion engine and the electric motor. On top of this, active aerodynamics will allow the cars to switch between low-drag and high-downforce modes via moveable surfaces on the front and rear wings.

"Of course, you'll have to master the new chassis and the new aerodynamics as best you can; that's the number one factor," he insisted. "But it's still the tyres at the end of the chain that have to absorb everything you do."

Tyre sizes will be reduced by 25mm at the front and 30mm at the rear to reduce drag and weight. But this also reduces the contact patch of the car. 

George Russell, Mercedes

Photo by: Peter Fox / Getty Images

"Having smaller tyres to reduce drag means the tyre is working harder," he continued before adding that the removal of tyre heating will also become a challenge.

"While we still want to run at very low tyre temperatures, without a heat blanket, as required by the regulations, Pirelli will still need to create a rubber that can handle the track well at lower temperatures than current tyres.

"So I would say it will probably be as important next year as it was this year, even though some aspects have changed for the better."

Pirelli has been testing narrower tyres with a 2026 mule car, but Mercedes driver George Russell wasn't impressed after testing in March of this year.

“A number of drivers have driven the 2026 tyres, which are going to be narrower tyres to try and help reduce the drag,” he said. “That was a bit of a challenge compared to the wide tyres we have today.

“It was quite a step worse with the tyres, naturally, because they’re just much more narrow. Hopefully they will be improved over the coming months.”