After the ITM Taupo Super440, the parity trigger for a review was confirmed by Supercars.
No changes will be made to the Toyota Supra, though Chevrolet teams are anticipating a change to the Camaro.
Ford has dominated the opening nine races of the season with seven wins. Chevrolet and Toyota have split the other two.
Speaking on Fox Sports’ Motor Racing 360, Ryan was asked whether Chevrolet teams deserved an adjustment, to which he replied, “Probably not.”
He added: “At the end of the day, I’ll be totally honest, we haven’t got any A-grade drivers.
“Some of the drivers won’t like hearing that, but they’re not A-grade drivers. We haven’t got multiple winners in our GM camp.”
Chevrolet has no current champions among its roster. Its most recent champion, Will Brown, became a Ford driver thanks to Triple Eight Race Engineering ditching the bowtie.
Its other champion, Brodie Kostecki, moved from Erebus Motorsport to Dick Johnson Racing last year.
It is widely known that General Motors has approached Ford and Toyota drivers in a bid to boost its ranks.
After Ford-bound Triple Eight relinquished the General Motors homologation rights, Team 18 took the reins. A seat is waiting there for Matt Payne should he negotiate a split with Grove Racing.
All the Chevrolet teams are aligned in the General Motors “camp” except for Erebus Motorsport, which has remained independent.
Ryan said he is well aware that neither of his drivers are ready to be race winners yet.
“Give us 12 months and if GM teams are winning and we’re still 20th, well, we’re doing something wrong. But we’ve got to be the first GM first,” he explained.
“That’s the main thing we want to try and do. And if we get to there and we can still only come 12th, well there’s probably something wrong.”
Ryan identified issues stemming from the off-season parity mission in the United States for what he said is a fundamental aerodynamic imbalance.
The Erebus Motorsport boss said he believed that the Chevrolet model would be used as the baseline for the wind tunnel test and that no changes would be forthcoming to the Camaro.
However, Ryan claimed the Supra was “too good” and that Supercars couldn’t move the needle far enough to match the Camaro, which necessitated changes.
“The only thing they could do quick was put a little bit more downforce on the front, which made the overall downforces equal but took too much off the rear,” Ryan explained.
“That’s my opinion – and pretty much talking to the other GM teams, they’ve got the same thing.
“We’re having to rob too much mechanical grip out of the front to balance the rear of the car and overall you don’t have the speed after three or four laps.”
The net result of the changes to the Camaro for Erebus Motorsport is a clean set-up sheet.
The team finds itself bogged to the bottom of the drivers’ championship with Cooper Murray 23rd and rookie teammate Jobe Stewart 24th.
“Unfortunately, GM allowed a change in the off-season, which shouldn’t have happened,” said Ryan.
“We were the incumbent (championship-winning) manufacturer, we shouldn’t have had a change.
“I tried to argue it but it didn’t matter. For some reason, we shifted the balance three percent to the front.
“None of our setups work anymore. We’re trying to get a set-up that we can work that (Stewart) can deal with as well as being a rookie.
“I’m not making excuses, but we should never have changed the balance and unfortunately they changed it and we’re stuck with what we’ve got at the moment.
“No one is asking for more downforce, we’re just asking for a shift back so we can balance the car up again.
Practice at the Christchurch Super440 gets underway on Friday at 7:35am AEST.
This article first appeared on Speedcafe.com, a sister site to MotorRacing.com.