What are the thinnest string gauges i should use to tune to drop c?

i have ernie ball beefy slinky strings right now...they are 11-54 gauge....good enough? or do i need the 13-56?

What are the thinnest string gauges i should use to tune to drop c?
I use 11's for standard tuning. Go for the 13's if you are doing drop C and are a somewhat experienced player. If you are still beginning, then maybe the 11's would be better.