I agree - finding the diameter of Acer griseum is oddly difficult to find online. Roger Phillips in "Trees in Britain, Europe and North America" doesn't mention it either. However, he does mention the height reaches 14m, but other sources mention that it rarely reaches beyond 10m in cultivation. One source: Michael Dirr's Noble Plants - Acer griseum The Acer griseum specimen in the E.H. Lohbrunner Alpine Garden, which measures approximately 6-7m high, has a dbh of roughly 24 inches, if that information helps.
