Well, Mk1 coaches weight around 35t, and a TSO can carry 64 passengers. Going on about 13 passengers per tonne, that makes about 40t maximum laden weight. They have the highest seating capacity, so oviously other types will weight a little less when loaded, although buffet/resteraunt coaches tend to be heavier anyway, and those with brake compartments the maximum luggage weight (usually a few tonnes) needs to be taken into account. If you're talking average as in with average loadings, somewhere around 37-38t would probably be about right. A 47 weights between 120 and 125tonnes.
