Ideal ATF Temp?

I have a 3000rpm converter in my daily driver. It's driven in the 110* heat out here in vegas. I currently have two trans coolers, one in front of the radiator. The other in a fenderwell with a electric fan on it.

Right now the fan is on a manual on/off switch. I already have a painless 185* on/170* off relay/temp sender deal that i didnt end up using. Would that be ok temps for the fan to turn on? Too high?

Thanks in advance.
-MIke