As in previous years, the event was also the second GT-only round of the IMSA SportsCar Championship season, in which only the GTLM and GTD classes were scheduled to compete.
On August 13, 2018, IMSA issued the latest technical bulletin outlining Balance of Performance for the event.[1] In GTD, the Ferrari 488 GT3 received a reduction in turbo boost and a fuel capacity reduction of 2 liters. No changes were made in GTLM.
The second practice session took place at 4:25 pm ET on Friday and ended with Antonio García topping the charts for Corvette Racing, with a lap time of 1:41.743.[5]
The third and final practice session took place at 8:35 am ET on Saturday and ended with Tommy Milner topping the charts for Corvette Racing, with a lap time of 1:41.205.[7]
1 The No. 93 Meyer Shank Racing with Curb-Agajanin entry was moved to the back of the GTD field for starting the race with a different driver than who qualified.
2 The No. 63 Scuderia Corsa entry was moved to the back of the GTD field after the team elected to change tires after qualifying.
3 The No. 44 Magnus Racing entry was moved to the back of the GTD field after the team elected to change tires after qualifying.