The local car spares guy informed me today that tints must not alter vision by more than 15%, therefore I could only have the two back windows and the rear glass tinted, leaving the passenger/driver's and front windscreen all transparent which would look really silly. The last sporting I had was blue tinted on all windows except front windscreen. I admit you had to develop 'night vision', but I never got pulled over. The guy also said that technically it could fail an MOT, depending on the strictness of the mechanic. Any advice? I would like to tint (when I learn how), but I don't want to waste my time and money if it is going to cause trouble. 