DIYers: minimum width tire for safety?

[TrevorB]

You have a motor rolling resistance doesn't matter unless touring where range is important. 2.15-2.4 will do everything but sand and snow while giving comfortable ride. Also huge range of tires to choose from. NB there is significant difference in volume between 2.0 and 2.15 Big Ben tires I have, not so much between 2.15 and 2.35.