This is where I went to find an inspection station in Maryland.
http://www.mdsp.org/services/inspection_stations_1.asp
If the link doesn't work....Google "Maryland State Police" and on there site you can find inspection stations by zip.
I still have to get my Jeep MD inspected but mine is all stock. A suggestion I would make if you haven't already had it inspected is to stick the stock rims and tires back on if you are concerned about the 31's. I went to a little shop for the inspection versus a dealership. Cost me $75 and the guy let me slide on the dark tint that was already on my car when I bought it.
Hope this helps.
-Corey