85 is the very minimum...thank you! I've just discovered that mine hides in temps over 90.
I always knew he was weird...
Are you measuring at 'top of shell' height, or on the floor? If the ground temp under the basking light is 85 degrees F, then it could very likely be just about perfect at top-of-shell height. When setting up a heat lamp, I always put a tortoise-sized rock under it, to measure at ground level and at shell level... so many tortoises end up with the top scutes burned together because of too-hot basking temps. Yay for infrared temp guns!