Depends on the year of bike and shocks, if you have one of the newer bikes you can put the full 50 psi in. With a no lost hand pump only, never try using a hose at a gas station or you'll blow the seals out of the shocks. I think 08 & earlier max pressure was 35 psi unless you have the low shocks like on the FLHX then max was 50 psi, you can alway let some air out for comfort, but @ 400lbs. I would expect 45-50 psi would be a good ride, just don't exceed the max.