If your car don't already come with tinted glass and is relatively clear, can try CR70 for front and CR40 for rear. Usually can clear inspection as CR70 allows ~70% of light, so after installing will be just slightly below 70%. The total solar rejection I think is about 20% more compared to CR90. But install at own risk hor.
From LTA website: "... Thus, tinted glass or films are allowed provided it allows at least 70% of light to pass through the front windscreen and side windows, and 25% through the rear windscreen and passenger windows."