With Saturday and Sunday morning practice sessions being added to the programme, in conjunction with a shortening of what was to have been a 90-minute hit-out today (Friday, May 17), a potential loophole regarding use of wet tyres has been closed.

The Further Supplementary Regulations 2 for the event state, in part (including mark-up):

1.2 GENERAL PRESCRIPTIONS – WET WEATHER TYRES 

1.2.1 At this Event, delete Rule D17.5.1 in its entirety.

1.2.2 At this Event, note the following amendment to Rule D17.5.2:

D17.5.2 A Car is only permitted to use W Control Tyres in practice, qualifying or a race if that Session has been declared wet by the RD.

Rule D17.5.1 of the Supercars Operations Manual states: “A Car is permitted to use W [wet] Control Tyres in any Session other than qualifying and a race at any time.”

The change to Rule D17.5.2, per mark-up, is the addition of practice to the stipulation.

Each driver is allocated seven new sets of soft compound tyres for this weekend’s event at Wanneroo, of which one is a ‘handback’ which is “not permitted to be used in qualifying or race Sessions” and hence six sets are available for use across the two qualifying sessions and two races.

Note also that the two sets of pre-marked tyres per car which teams are allowed to bring are also for practice only.

With knockout qualifying both tomorrow and on Sunday, though, that is six segments of qualifying in total, while practice sums to 100 minutes over the course of the event, and Wanneroo Raceway is regarded as one of the tougher circuits on the calendar with respect to tyre wear.

As to why one would burn through wets rather than simply sit out a non-competitive session, one possible explanation is that the existence of Saturday and Sunday morning practice provides an opportunity for a systems check in the hours before qualifying.

With that window of opportunity closed, it is highly unlikely wets will be seen on a race car this weekend, aside from activities such as wheeling it in or out of a transporter, given weather forecasts are for dry and mostly sunny conditions throughout.

This is not the first time in the last 12 months that Supercars has clamped down on fitment of wet tyres, with PremiAir Racing exposing a loophole in a Top 10 Shootout at last July’s NTI Townsville 500.

However, the wet track declaration rule dates all the way back to 2015, when the Walkinshaw Holden Racing Team fitted wets on James Courtney’s Commodore during a sprint race at Winton given an earlier incident had put him a lap down.

The Wanneroo supplementary regulations contain another exception to the usual rules, with respect to track limits, although that has applied for the Perth event for several years now.

If a driver breaches track limits at Turn 7 during practice or qualifying then not only that that lap time but also the subsequent will be deleted.

The rationale is that a wide exit, behind the kerb, allows drivers to carry speed for the start of the following lap and hence gain an advantage by deviating from the race track proper.

Practice 1 starts today at 14:20 local time/16:20 AEST.