I've always found it an interesting convention, though, that the coinage of the Gallic emperors and other (even the most transient) usurpers is considered to be so, and as such consequently cataloged on an equal footing..
Just for comparison's sake, here's a genuine Tetricus antoninianus of mine. Its dimensions are 19 x 17.5 mm, with the weight coming in at 4.3 grams. I have it as RIC V 127.