change tyres is not count by year honestly. You need to change tyres if:
1) pattern is less than 3mm deep. or
2) 4 years after manufacturing week printed on the tyres or
3) feel slippery on wet road.
Tyres are the main thing to let you handle the car, if the tyres lose it's function, no matter how good your driving skills or how good is your car, you will have accident easily and affect your family and other road users.