CREATE TABLE table_71112 ("Year" TEXT, "Start" TEXT, "Qual" TEXT, "Rank" TEXT, "Finish" TEXT, "Laps" FLOAT)

What is the highest laps with a 30 finish?
SELECT MAX("Laps") FROM table_71112 WHERE "Finish" = '30'
SELECT MAX("Laps") FROM "table_71112" WHERE "Finish" = '30'