OK, so I consulted the FAQ, and here's a blurb:

The technical specifications, directly from the Rio Car web site, are as follows:

Operating range (disks spinning and being read): 5ºc (41ºf) to 55ºc (131ºf)

Standby range (disks spun down): -20ºc (-4ºf) to 60ºc (140ºf)

It looks like 55ºc or 131ºf is our drop dead maximum, so what do you think, set the max at about 50ºc or 121ºf?