Time trials are timed qualifying laps run against the clock rather than against other cars, usually two laps per driver, with the resulting times setting heat race lineups or, at some tracks, the feature lineup.
Two laps is the common number, not a universal one. World of Outlaws sprint car and late model drivers each get “two timed laps” to set heat lineups. The American Sprint Car Series and Super DIRTcar both run “two consecutive timed laps unless otherwise noted,” and ASCS reserves the right to switch to multi-car qualifying. Slinger Super Speedway splits it by class: three laps for Super Late Models, two for most divisions, group qualifying for the entry-level classes, and no qualifying at all for Figure 8s. Plenty of weekly shows skip it — Hartford Speedway lines up heats by pill draw “on non-qualifying events.” Be on time, too: ASCS cuts a late car to one lap and caps it at fifth in its heat.
Time trials compress your whole night into two laps, and at a track that lines up straight off the clock, a tenth you left out there follows you all the way to the feature.