Why standing waves and tyre graining will be huge challenges in Vegas
Formula 1’s much-anticipated inaugural Las Vegas Grand Prix will be a “jump into the unknown”, according to Pirelli, as very cool temperatures and long straights may potentially deform the tyres.
Thanks to a mid-November calendar slot, and the decision to hold the charge along the famous Strip at night, the air temperature will most likely drop well below 10 degrees Celsius for all track sessions.
The earliest, and therefore most likely the warmest, run out is first practice. That kicks off at 20:30 local. However, the lights won’t go out for the GP until 22:00. A two-hour limit will take it to midnight.
F1 and Pirelli have dealt with similarly cool conditions before - think the 2020 Eiffel GP at the Nurburgring when the race took place at a balmy nine degrees. And there’s been plenty of winter testing where beanie hats and thick team-branded puffer coats were very much in vogue.
What’s different for Sin City, though, is that the 3.85-mile lap is dominated by long straights topped in smooth asphalt. Combine these with an absence of high-speed corners and it means the winter air will have plenty of time to chill the tyres, while there’s precious few areas for drivers to warm them back up again.
Given the lack of exact historical comparisons, Pirelli is working with data from the FIA, F1 and teams in an effort to prevent tyre graining and shaking from becoming a distracting sideshow all weekend.
Pirelli motorsport boss Mario Isola explains: “We had in Barcelona some pre-season tests with similar temperatures, but Barcelona is a different circuit where you put more energy into the tyre.
“Also, the asphalt I remember at that time was quite aggressive. It was before the last resurface. So, in Las Vegas, I believe we’re going to find it quite a unique situation compared to our historical data.”
Where the tyres may come unstuck
Owing to the long straights that typify the lap, there will be protracted periods where little energy is being exerted on the surface of the tyre. No braking zones, no lateral forces. This will allow the ambient conditions to lower the external temperature.
Previously in Baku, which is perhaps the closest companion in terms of track layout, tyres have cooled by over 30 degrees through the flat-out final sector. And like in Azerbaijan, because the Pirellis will be rotating at speeds north of 200mph, the bulk temperature (inside the tyre) will be far higher.
With the tyres then not optimised for the corners, the cars will be prone to oversteer and/or understeer. As the rubber drags across the top of the abrasive, more road car-biased asphalt, it will grain to keep surface tears and rips high on the agenda. The lack of temperature will also extend braking zones and make lock ups more likely.
“Are we able to keep the temperature in the tyre?” says Isola. “These factors could generate some graining.
“The track layout, we were working in advance compared to the usual procedure to get simulations in order to understand the severity of the circuit. And it's confirmed that the circuit is high speed but is a low severity in terms of corners because you don't have like in Silverstone high speed corners where you put a lot of energy.
“The Tarmac is not completely a road Tarmac but should be quite low roughness. So, Tarmac roughness, layout and colder temperature means that we are not generating a lot of heat into the tyre. That means that you cool down the tyre in the long straight.”
This thermal headache will only be more pronounced in the event of the field having to slow down for a virtual of full safety car.
He adds: “The point is that on the straight line, you generate standing waves [ripples in the sidewall as the tyre deform]. So, we need to protect the tyre from this high speed and the standing wave.”
Prevention is better than curing
In preparation, Pirelli has sought transparency from the FIA, championship and competitors. When teams completed their simulations, they fed back information to the tyre supplier. This, when appropriate, was then shared by Pirelli to the other parties. Given the high expectations that encircle the Las Vegas GP, it’s in no one’s interest to knowingly let a shambles unfold.
Pirelli have also submitted the three softest-available compounds for the event: the C3, C4 and C5. While the obstacle still remains that there are only six different types to cover an entire calendar, one that will stretch to 24 different circuits next season, the stickiest and most malleable rubber should help teams in their bid to keep some heat in the tyres.
High pressures will also be mandated. This will add some stiffness to the sidewall to make them less prone to the tyre-shaking sensation that comes with standing waves.
One area of change that was evaluated but not pushed through was the management of tyre blankets. There were talks of increasing the cooking temperatures above 70 degrees to keep the tyres hotter at the start of a stint. Consideration was also given to allowing the blankets to be left on overnight. This would allow the cured rubber to retain the heat for longer.
Isola explains: “We decided to select the three softest compounds simply because the temperatures are expected to be very low… We discussed [the tyre blankets], and I believe we don't need to allow them to do something different. We have the blankets. Seventy degrees is a temperature that allows you to go out with a tyre that is a good level of grip.”
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