Hello,
as Curtisi mentioned earlier, by default LEM warns the users about running out of free space when used space is less than 10% (LEM, OS& Temp partitions) or 10GB (Logs/Data partition).
But since LEM v6.3.0 the users are able to define their own limits per each partition, see "Create a disk usage warning when reaching certain set values" chapter at LEM 6.3.0 Release Notes - SolarWinds Worldwide, LLC. Help and Support . After that re-configuration no new custom rules are needed.
I would also recommmend that you firstly run CMC - appliance - diskusage command to see actual disk usage in [%] as well as in [Bytes].
Milan