The radius on the steer tube is smaller than that of e.g. a bottom bracket, so it is not a foregone conclusion that a lockring wrench designed for a bottom bracket will work. The hinged lockring wrench I referenced can accommodate a wider range of tube diameters. Hozan also made a double-ended lockring wrench that accommodated bottom bracket diameters on one end and headset diameters on the other, but it's more expensive than the hinged wrench I referenced: