Transmission towing temperature - Scan Gauge II

So I'm looking to tow long distances and I was wondering at what temp I should pull over and let the temperature cool off before going again, on mountain roads. I have a Scan Gauge II on order but I think it only gives me a temperature number, not a warning of when it's too hot. So I thought it would be best to ask.
Thanks in advance.

 

There’s more to it than “just temps”

But as a general rule -Below 220 if possible.

 

Awesome thank you for that

 

Excellent write-up here about trans temps and the need for additional cooling when towing by @gearcruncher.

 

Good stuff thanks

 

Pick up a Derale transmission cooler and then Worry much less about it.

 

Well I have a oem cooler on it and not sure I want to mess with the trans. As the last shop may have under filled it a bit. I hope to not tow that much weight for this trip cross country. I'm just moving furniture. My concern was mountain passes.