If braking and cornering is still good then no need to replace, old rubber tends to puncture more easily and gets dry rotted (cracks)
If just noise is an issue then it's not really a case for replacement unless you have 4-5 passengers on highway more frequently.
For local use under 80kmph keep driving it just dont take it on a highway thinking they will give a peaceful ride.
If alignment is good and wear is normal just remove the rear tyres (with better tread) and move them to front wheels and vice versa. Check "tyre rotation" process on youtube.
Considering the current prices of size 16 tyres in Japanese or Imported brands i'd say get another 5-10k kms out of it.
Replace them with Yokohama, Continental or Bridgestone only.. As chinese or local tyres have much lower quality rubber and after 1 year mark they become hard and noisy.
Personally experienced Michelin 4 years 90k kilometers and still 30% tread left and Yokohama ES32 2 years absolutely noiseless and comfortable tyres zero punctures thus far but not recommended for rough roads.
