I can just barely get my desired withdrawal with 100% success using 0% equities. Worst case prediction for my plan is $9K portfolio value at the end of 30 years if using 0% equity.
A related but unasked question is why ? IMO its a rather non-sensical question. 0% equities is not the safest portfolio allocation and is just the opposite of diversification. If I was "I've won the game and don't wish to play anymore", I would adopt a 20-80 portfolio. The lowest overall risk portfolio according to Efficient Frontier studies.
I get Firecalc higher ending portfolio balances and/or higher permissible withdrawal rates using higher equity allocations. I've been 60/40 for years, but I'm currently on a "rising equity glideslope" by spending just from fixed income. I expect to be 70/30 by age 70 (5.5 years). But 0% equities? Not even a consideration for me. But yeah, I could do it.