P = passenger tire
205 = tread width in mm
55 = aspect ratio, basically a percantage of the tread width, so your sidewalls are about 113 mm tall, which is 55% of 205. The lower this number, the lower the profile relative to the tread width.
R16 = 16 inch wheel/rim
89 = load rating, can be looked up in a table
H = speed rating, can be looked up in a table

So if you want something more low profile, get something with a lower aspect ratio.