Keep it in the 70s unless you want it to break and have a short life
Or maybe just abuse them till they die
, personally, I did not have much difference between running those low-quality gears cold vs hot, they all died way too soon. 
I think the Asic chip max temp for the 17 series is usually around 110c-135c.
Mind sharing where you got those numbers from? I am almost certain that no Antminer 17 series miner could run for over an hour at anything nearly 110c, let alone 135c.