Pumping up your road bike tires? Keep pumping, it takes a while. Forty, 50, 60 pounds of pressure per square inch. You can drop that for your mountain bike. Thirty pounds, 35 – maybe 40 PSI, if your cranking a lot of hardpack.

But for your fat bike, simmer down. Those big tires won’t take much.

Joey Ernst of Velorution Cycles and Bedrock Bags in Durango says to go low. Way low.

“Tires pressure is super crucial,” Ernst says. “It is the No. 1 thing that determines how a fat bike rides.”

Ernst prefers tubeless tires. You can run even lower pressure and they won’t go flat nearly as easily.

While there are tire gauges made specifically for fat bike tires, Ernst recommends getting to know pressure by pure feel. He likes about a pound and a half PSI, and using his thumbs to gauge the pressure when he’s adding or releasing air, he knows exactly what he’s looking for. But it’s fun to test anyway.

“One and half PSI,” he said, pulling the gauge off the tire stem on his personal bike.

“When it comes to fat bikes, it’s all about the tires. You have more surface area with the larger tires, so you can run much lower pressure, and that tire spreads out over the snow surface allowing you to have more flotation,” he said.

Ernst said there are various treads, some made for trails and dry conditions, and others made purely for snow. He added that with most normal mountain bikes tires, a few PSI might go unnoticed, but with a fat bike, as little as half a PSI can make a huge difference.