The modelshops in the UK seem to prefer VDI Scale and/or RA scale…
VDI Scale goes from 12 (which is smooth) to 45 (which is more rough)
RA has to do with the size of the bumps that make up the texture. 18 is like Sandpaper and .4 is very smooth
Most people can do their equivalent of MT textures if you spec that though. If you’re friendly with them there’s usually there are urethane casts of the MoldTech texture sample panels floating around that they can give you for next to nothing