Before I installed my engine I noticed my front tire was flat. I had assembled eary in 2018, so I figured it had a slow leak. I inflated it and ordered a new tube. A few days later it was flat again.
I removed the wheel and disassembled it. I inflated the tube, ran soapy water over it and found the leak where the valve stem enters the rubber tube.
I partially inflated a new tube, inserted it over the stem half of the rim and into the tire. I then assembled the other half, torqued the 6 nuts and installed the center o-ring. I then inflated the tire to 2 bar, deflated to 1 bar and then inflated to 2.5 bar per the manual.
I let it sit a day or two to check the pressure before installing it.