North Wales Police are warning drivers who have their windows tinted to make sure that the work satisfies the law on visibility.
A spokesperson said: "Earlier today we stopped a driver in the Llandudno area as we noticed he had heavily tinted windows on his vehicle.
"The law states the windscreen must allow at least 75% of light in with a 70% limit for side windows.
"Upon closer inspection, and with the use of the equipment we have that can measure light transmission through glass, it transpired the front offside and front nearside windows only allowed 16%.
"The driver was handed a ticket and words of advice, though we could have seized the car for being in a dangerous condition.
"If your windows don't conform to the legal requirements expect to be prosecuted. If you are in any doubt whether the windows on your vehicle are lawful, we would suggest you have them checked by a reputable garage."