Michelin IMSA Insider: The Four “Ts” of Long Beach

After a 2,600-mile cross-country trek from Sebring, the IMSA WeatherTech Championship GTP, GTD Pro and GTD teams will take to the streets for the Acura Grand Prix of Long Beach where victory often comes down to a combination of four “T”s.

Track Position: The 1.968-mile street circuit provides limited passing opportunities, and the short race duration of 100-minutes has most teams planning a single pit stop. Teams put a high premium on qualifying and may go off strategy to improve track position by getting their driver out of traffic and on a clearer track.

Teams have won at Long Beach by changing one, two, or four tires, or even by skipping the tire change and going the full distance on a single set of Michelin race tires.

Traffic: With 28 cars entered, 20 in GTD Pro or GTD classes, the field will likely be closely bunched, as drivers fight for position or run in packs, making getting through traffic critical for the GTP runners.

The new GTP cars from Acura, BMW, Cadillac, and Porsche expect to lap the Long Beach temporary street circuit in the 70-72 seconds per lap range while their production based GTD and GTD Pro counterparts are in the 78-80 second range.

At the race start or any restarts, the GTP hybrid drivers will find themselves encountering the tail of the GT pack after just six or seven laps and then in near constant traffic for the remainder of the race.

Like the Long Beach Harbor where the tide will be rising, race traffic will ebb and flow as gaps open, then disappear. Cars caught in traffic can lose 3-5 seconds in a single lap.

The speed differential between the GTP, GTD PRO and GTD classes and resulting traffic is magnified on the concrete barrier lined street circuit where this weekend’s IndyCar race has a similarly sized field, but with identical cars and only Chevrolet or Honda engines.

Timing: Most GTD teams initially plan to do the 100-minute race with a single pit stop. Teams will look to refuel, change drivers, and possibly tires all in one shot. That plan can quickly change in the event of a full course yellow (FCY). The minimum GT class drive time is 35 minutes.

For the GTP teams, a FCY raises a decision whether to stay with the hot set of tires on the car or go with the cold second set of the new Michelin double-stint tires on the pit wall.

Tires: For GTP teams the magic number is two. Teams will have just two sets of the proprietary new Michelin Pilot Sport Soft High Temperature (SHT) double-stint tires for qualifying and the race.

Although GTP teams are permitted to use both sets in qualifying, some may choose to run just one set of tires in the 20-minute session late Friday afternoon, while others may make a short run on the second set.

Any contact, lockups, debris, or brushes with the wall can limit tire strategy options as will any handling issues.

GTD cars are allocated five sets of the commercially available Michelin Pilot Sport S9M race slicks for the event with all five sets permitted in the race.

While the 2022 race saw hot, sunny weather with track temperatures reaching 127 degrees, the preliminary weather forecast is for partially sunny conditions and ambient temperatures in the high sixties.

Unknowns entering the weekend are the impact, if any, of recently resurfaced sections of the circuit on grip and tire wear, and the interaction, especially early in the race, with residual rubber, including marbles, from other series as the as 2:05 pm (PT) Saturday IMSA race start follows IndyCar qualifying.