Based on articles I've read, about 5 years.
Metzeler's warranty states:
What is not covered: > Tires with weather/ozone cracking which were purchased more than four years prior to presentation/inspection for adjustment. (If no proof of purchase date is available, the warranty will be four years from the DOT date.)
I am not sure if this pertains to India.
2013 Ninja 1000 - White/Black "33"
2007 VTX1800C - Black/Chrome "Super Grom"