The rule of thumb is to use a Total Virtual Memory Limit which is about 95% of the physical RAM on your machine.
With regards to the ratios/percentages, for "normal use" I'd return these to how they were before you modified the Virtual Memory Limit.
Use this as a starting point and then address any memory related errors, should they arise, by adjusting the percentages. Always make sure that the percentages add up to 100% at the bottom though.
To use manual memory tuning, automated memory tuning has to be turned off by
setting the Memory.AutoSetting to 0 in the global I-DEAS parameter file. The
DEFAULT location for this file is: