Max. Range difference B767.300ER vs. B767.300F

[despegue]

When looking at the Boeing.com supplied range charts and technical figures for both B767.300ER and B767.300F, I notice a severly reduced maximum range for the freighter version compared with its passenger counterpart, although they can carry the same amount of fuel ( around 90.000kg.).

Can anyone explain this to me?

[oceancrosser]

Haven't looked at the charts, but could it be that the freighter charts assume maximum payload whereas the chartsfor the pax version assume a typical two or three class load (210 pax) IIRC? Pax are a fairly light payload vs all cargo.
I have yet to fly a 767 that takes 90 tons of fuel, just under 75 is the max I have seen.

[Meikleour]

Freighter versions of aircraft typically operate at closer to their max ZFW than their passenger equivalent. A classic B747F could carry almost 110 tonnes whereas the weight of a load of pax + bags would be more in the 50-55 tonnes range. Given equal max TOW then there is less scope for fuel - hence less range!