user: Question: What is the largest grid with a Driver of ralph firman, and a Lap smaller than 18?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Giancarlo Fisichella', 'Jordan - Ford', 54.0, '1:31:18.2', 8.0]
SQL:

assistant: SELECT MAX("Grid") FROM "Table" WHERE "Driver" = 'ralph firman' AND "Laps" < 18.0;