You need to open the .HDV file and edit (or add if its not present) the below lines (they are in PITMENU section):
FrontWingTime=(8.0,8.0) // Time to adjust front wing, time to replace front wing; default=(8.0,8.0)
RearWingTime=(8.0,33.0) // Time to adjust rear wing, time to replace rear wing; default=(8.0,33.0)
First number : time to adjust
Second number : time to replace/repair
Note: Changing this lines will produce mismatch in online racing.