Get the jumper cables out. But seriously, with the exception of big box store bikes, most fatty tubes are Presta.

FWIW, on my bike, I use the gauge as a reference and a starting point (5-6 psi) and drop the pressure from there as needed for conditions. With winter riding, pressure can vary greatly with temperature changes - never adjust your pressure until the tires have acclimated to the outdoor temperature. With that, there is no real need for a gauge as you will just be squeezing the tire to guesstimate if you have let enough air out.