Explained: Supercars’ AGP tyre loophole
Friday 31st March, 2023 - 6:00am
Erebus Motorsport almost snatched victory while Triple Eight attacked with one car and defended with another using a loophole in Supercars’ regulations for the Beaurepaires Melbourne SuperSprint.
They pulled off the trick, as did Brad Jones Racing, thanks to a unique set of circumstances and cleverly exploiting the rules for the Formula 1 Rolex Australian Grand Prix weekend, as we will step out here.
In particular, we will highlight the change in the Further Supplementary Regulations which made it all possible.
To begin, let us consider what would ordinarily have happened from a strategic standpoint in any of this weekend’s four races at Albert Park.
Every driver would have started on super soft tyres and switched to hards to finish the race, or vice versa.
That is not a strict requirement – it is permissible to change from super soft to hard and back, for example – but either of the aforementioned single-stop approaches are the only rational ones absent any misfortune or unusual factors.
Supplementary Regulation 5.8.2 states, “At this Event, Teams must use at least four (4) SS Tyres and at least four (4) H Tyres during race 3, 4, 5 and 6,” while Schedule A2, as varied by Further Supplementary Regulation 1.3.1, stipulates that a minimum of four tyres must be changed in at least one pit stop in each race.
So, how did we get to a point where some teams only changed two tyres and replaced the outgoing tyres with those of the same compound?
As has been well-ventilated now, Race 3 was officially declared wet, a practice introduced several years ago when competitors were banned from running wet tyres on a dry track to save on slicks (usually done if already in an especially uncompetitive position in the race in question).
Per the 2023 version of the Supercars Operations Manual, that is covered by Rule D17.5.2.
Under the Supplementary Regulations for the event, when Rule D17.5.2 was declared, Supplementary Regulations 5.8.1, 5.8.2, and 5.8.3 no longer applied, nor did a rule which the Supplementary Regulations created regarding notification of tyre compounds.
Supplementary Regulation 5.8.1 pertains to qualifying sessions (and hence is irrelevant for the purpose of this piece), 5.8.2 is reproduced above, and 5.8.3 is essentially a reminder that the Operations Manual prohibits mixing tyre compounds on a car, which means the rule (D17.1.10) still applies regardless.
However, the requirement to change four tyres would have remained.
Triple Eight, for example, could change from super soft to super soft, but would have to change all four corners, and hence the only gain would be the small increase in lap speed on an out lap (when tyres are cold) and perhaps one more, at the cost of using tyres which will need to be rolled out again in another race.
What the Further Supplementary Regulations did, however, was change the CPS requirement such that only two tyres need be changed, if the track was declared wet.
That – specifically one rule within Further Supplementary Regulation 1.4.1 – is the critical change to the rules for the weekend which enabled the strategy play from Triple Eight, Erebus, and BJR.
Given there is only one compound of wet tyre, the provision is consistent with the rules for pit stops at sprint races with just a single slick compound, in which two tyres are the minimum requirement.
However, a race which is declared wet is not subsequently ‘un-declared’ wet.
The threat of rain and/or the sprinkles which did occur on the formation lap, while otherwise not really being a factor, did ultimately have a major say in how the race played out.
Perhaps, in future, the (Further) Supplementary Regulations for Albert Park will stipulate that when Rule D17.5.2 is declared, the minimum CPS requirement is ‘2W or 4H or 4SS’.
Of course, that only closes part of the loophole, that being around the quantity of slick tyres changed (as opposed to specifics around use of compounds).
To close it completely, the regulations would need a stipulation such as, “At this Event, Teams which use more than four (4) SS Tyres must also use at least four (4) H Tyres, and vice versa, during race 3, 4, 5 and 6.”
So long as there is a minimum two-tyre CPS requirement also (and the prohibition against mixing compounds remains), the rule would function as intended in dry, actually wet, or dry but officially declared wet races.
Unless there was some massive discrepancy in pace from compound to compound, the fastest way to complete a dry race would be one set of super softs and one set of hards, meaning just the one pit stop.
But, would we event want to tighten up the rules so much?
Arguably, part of the fun in motorsport is exploiting the grey areas and loopholes.
What is also interesting is the motivations of the aforementioned teams in Race 3.
Two used the loophole to attack (gain track position), while Triple Eight used it to attack in the case of Broc Feeney and defend in the case of eventual race winner Shane van Gisbergen, who was followed into the lane by Erebus’ Brodie Kostecki.
Race 3 was also the culmination of a particular set of circumstances, including the unexpected longevity of the super soft compound.
If it had degraded such that it was slower than a new hard tyre at some point relatively early into a 19-lap race, we might have seen a 2020-style scenario where a team robs Peter to pay Paul.
Instead, it was possible to maintain race pace until there were no later opportunities to take the CPS, and there was thus little cost in using another two super softs on the rear (noting also that Races 4, 5, and 6 are shorter than Race 3 anyway, and those extra super softs from Race 3 can be put on the front in one of Races 4, 5, or 6).
Notably, more rain is forecast for Melbourne today, with Race 4 scheduled to start at 14:55 local time/AEDT.
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