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GT300 Four-Tyre Mandate Removed After Just One Race

BoP changes announced in GT300

Super GT’s controversial pit work rule that mandated the exchange of all four tyres during the compulsory pit stop will not apply for the upcoming third round of the season at Suzuka Circuit and beyond.

It would confirm that the four-tyre rule, which was introduced ahead of the second round of the season at Fuji Speedway on 9 August, was put into place as a safety precaution following a string of tyre failures in the opening race of the season (also at Fuji). Round 2 proceeded with no major tyre issues, and crucially, Super GT’s tyre manufacturers had even brought in different compounds of tyres to the circuit with an emphasis on safety.

With that assurance of safety, the four-tyre mandate was dropped for next week’s race at Suzuka on 23 August.

The rule was perceived to be at the detriment of the JAF-GT300 and JAF-GT Mother Chassis entrants, who had often gambled on two-tyre or fuel-only pit stops to gain track position, as Saitama Toyopet GreenBrave had done to win Round 1. Ironically, the race was led, virtually lights-to-flag, by the JAF-GT300 Subaru BRZ and the Mother Chassis cars – including the winning Mooncraft/Lotus Evora MC of Cars Tokai Dream28.

Now the teams which had been accustomed to alternate tyre strategies can do so again, starting next week. But considering that Suzuka is a circuit famous for high tyre degradation, a two-tyre or no-tyre stop might be a stretch, even for cars on harder compound tyres.

As a countermeasure, the Balance of Performance has been updated for the JAF-GT300 and Mother Chassis cars. The fuel flow restrictor on their refuelling devices has been reset to 27.5mm for Round 3 and beyond. JAF-GT300 cars were exempt from the restrictor in Round 2, and Mother Chassis cars had their restrictor size increased to 31.2mm in the same race. The larger fuel flow restrictors were allowed with consideration of the four-tyre mandate at Fuji.

Some of the other BoP changes are as follows:

JAF-GT300 Mother Chassis (MC86, Evora MC): +30kg minimum weight
Honda NSX GT3: -30kg weight, boost pressure up
Aston Martin Vantage GT3: -15kg weight, boost pressure up
Audi R8: -15kg weight, air restrictor (41mm x 2 > 40mm x 2)
BMW M6 GT3: -10kg weight, boost pressure up
Lamborghini Huracán GT3 EVO: air restrictor (40mm x 2 > 39mm x 2)
Lexus RC F GT3: -15kg weight
Mercedes AMG GT3: -10kg weight, air restrictor (36mm x 2 > 34.5mm x 2)
Nissan GT-R GT3: +5kg weight, boost pressure up
Porsche 911 GT3-R: -15kg weight, air restrictor (43mm x 2 > 41.5mm x 2)

Feature image courtesy of the GT Association