You'll find that it's a trial and error process as you want your alarms set slightly outside your normal operating range. For instance, I run the Goodyear G114 tires on our 5th wheel at 120 PSIG cold. I have to run the high pressure alarm at 145 PSIG to avoid nuisance alarms during Interstate driving in Texas summer conditions as I will routinely see hot inflation pressures of 138-142 PSIG. On the other hand, the truck's tires don't seem to gain over 5 PSIG or so from their 65 PSIG cold inflation pressure.
I think I set the low pressure alarm at 10-15% or so below the cold inflation pressure. That's the one you're really interested in, of course.
TST recommends leaving the high temperature alarm at its default setting (~157 degF, IIRC), so I did. Their rationale for this temperature alarm setting is they claim to have talked to tire manufacturers who state that no thermal damage should occur below this temperature. To the best of my knowledge, there's no low tire temperature alarm - why would there be?
Rusty