Tandy, who is sharing the #6 Porsche 963 with Dane Cameron and Mathieu Jaminet for this weekend's IMSA WeatherTech SportsCar Championship curtain-raiser, observed how limited running has been on Michelin's new low-temperature soft tire in the build-up to the event.
The bulk of pre-event running with the new LMDh prototypes has been done with the high-temperature soft compound, and Tandy believes some cars could suffer more than others during the nighttime running that makes up the bulk of the Florida enduro classic.
"We ran the cold soft [on Thursday night] in practice, and that was the only session we could use it, because the night session at the Roar [pre-event test] was wet," the Briton told reporters on the eve of the race.
"There is a balance shift between the two tires as you would expect, but for all the teams it’s the first time we’ve run on this tire. We’ve got to do 13 hours of the race on it, and we haven’t really tested it!
"The end of the race we’ll be on the soft-hot, so I think everyone is setting their cars up based on that and just accepting there may be a balance shift when you switch to the cold-spec tire in the night.
"But you could see the pace of the cars changing quite dramatically depending on the tires we’re on. If one car struggles to put energy in the front tire, they could struggle on the colds, but others could struggle to look after the rear tires on the hots."
Tandy however conceded that the nature of IMSA races, with frequent caution periods offering chances to catch up to the leaders, mean that being fast at the end of the race will be the priority.
"It is about the last six hours," he said. "You can’t afford to just cruise around and fall a lap down, but as long as you can stay on the lead lap in the night, it will be when we go back on the soft-hot [tire] in the daytime that will define the positions at the end of the race."
Wayne Taylor Racing's Filipe Albuquerque is also expecting the new tires to provide a major challenge during the Rolex 24, as well as the expected increase in stint lengths.
A typical stint for the GTP cars is now expected to run for 50 minutes to an hour, depending on caution periods, compared to 35-40 minutes during the DPi era. The reduction in available tire sets - 33 for the whole weekend and 21 for the race - also means teams will have to double-stint tires.
“One thing that is tricky is that with new tires it's very slippery getting out of the pits," said Albuquerque. "We've seen Helio [Castroneves, Meyer Shank Racing Acura] spinning in the pitlane [during Friday morning practice] – that's how slippery it is.
"So it's going to be interesting to deal with that, especially when the things are starting to get more heated up with racing and track position. It is easy to do mistakes.
“I think we will learn through the race how much time we lose on cold tires, how much we lose by having to double-stint tires. It's new for everybody and we could never really do a proper long run and double-stint tires because this compound was new in December. It's not that we were working with this compound before.
“Again, it's the same for everybody at the end of the day, so it's going to be curious to see who really nails the set-up and the strategy.”
Additional reporting by Charles Bradley
