WS 767 MTOW only 172,365 kg, as i suspected, much lower than on AC's newest 767s (186,880 kg).
These birds will have a hard time on any Alberta-China runs.
http://wwwapps.tc.gc.ca/saf-sec-sur/2/ccarcs-riacc/ADet.aspx?id=528663&rfr=RchSimp.aspx
Even AC's oldest 767, C-FCAB, built in 1988, has a 181,439 kg MTOW.
According to the Boeing ACAP document for the 767, seems like 172,365 kg was the initial weight variant on the 763ER. So most likely QF ordered these lighter birds as they probably didn't need any additional lift back in the day.
Different weight variants:
172,365 kg (WS)
175,540 kg
181,437 kg (AC's oldest 767)
184,612 kg
186,880 kg (AC's newest 767)
Based on the payload/range charts, anything greater than 5000 nm (still air) is a no go for this WS bird. YVR-LGW is 4126 nm. Although the westbound leg could easily reach 4600-4700 nm still air distance factoring in the headwinds.
Plenty of legs for Alberta-Hawaii though !