Let topicstarter give the answer before we spend 2 pages on the discusion about it. But risking that , I dont understand the 3.7 ton being set over to 7400# , and even dont know what # means in this notation.
3364 then again in KG would be the GAWR and not the empty weight.
this weight is that close to GVWR that you cant speak of any loadcapacity.
I agree with your first post here that 4 point weighing ( loaded as you use it) is the best way to determine the loads for determination of tire-pressure, second best axle-weighing, but as long as you did not do that , you will have to do with the GAWR/MPAW to determine a pressure going from the idea that you are not allowed to go over your GAWR's to law. In my spreadsheet I use in case of only GAWR given , rear a reserve of 18% , to cover overloading, wich is not allowed by law, but practice proves that Rear axles of motorhomes often are.