Is it safe to ride on cracked tyre? I have a cracked tyre on my Road bike. I think I put it in the gazebo and exposed it to the sun.

It's cracking along the tyre wall, in continuous fashion. 



Would it be safe to ride on those crack tyre? As they are fairly new, I don't want buy a new one if it is ok to ride, i.e. no catastrophic failure.
The cracks will expose the internal structure to elements. So yes, they are not going to last as long as non-cracked ones but very probably not going to explode right away either.

The Nokia tires that used to be popular in my country developed cracks between tread and sidewall after a few months' use and could still be ridden for years afterwards. Your mileage may vary.