It's not a good idea to use a standard set meant for all fourths tuning, since most have a lowest string that is looser than the other strings, dropping that string a tone then reduces tension by 21% making it excessively floppy. Consider a set purpose designed for a drop tuning which has the lowest gauge increased to compensate for the drop, to create equal tension strings. Circle K Strings have a big choice here:
vStandard Drop-tuned 4 Strings, the gauges look strange but are carefully chosen to create equal tension strings. They have a short taper so check compatibility with the Warwick bridge:
http://circlekstrings.com/CKSIMAGES/CircleKspecs.pdf.
Or use the D'Addario tension chart:
http://www.daddario.com/upload/tension_chart_13934.pdf to choose gauges that give you equal tensions in CGCF. You can use those charts to approximate the tensions of other brands. Look up the tension of your favourite gauge E string and use that tension value to choose gauges for CGCF.
For example if you like a 100 E, that's 36.5 pounds (using the chart for XL nickelplated roundwound), so choose 125 85 60 45. Or 105 E 40.3 pounds -> 135 85 65 50.
Here's a good place to
Build your own string set!
