AT the FTA training the proper care and feeding of tubes was discussed. Each field is shipped with four ac powered inflaters and a custom made 'fill' tube. They also ship a plywood fixture for 'sizing' the tube. The idea is to inflate the tube until it is just 'snug' in the fixture. The fixture looks like the letter 'U.'

Bottom line is there will be some variation in the inflation pressure - so deal with it.