What an absolute mess. I’m a technical nerd, and I can probably do the research necessary when I need a new card... but we expect ordinary people to figure it out? Not likely.
205 is the approx width of the tread in mm
55 is the height of the tire, expressed as a ratio reletive to the width
r usually meant Radial type tire, but has just become part of the standard notation iirc.
17 is the inner diameter in Inches
96 is the Load rating expressed as non linearly scaling variable, needing a chart,in this case 1565lbs.
R is the speed rating, which is usually, but not always in alphabetical order due to weird grandfathered codes. In this case, it means the tire is safe to speeds up to 106mph.
While not hard, it is complex. You can run a taller(sometimes) or shorter(usually) sidewall, or wider(often) or narrower(almost always) tread (within reason), but you can not under rate the load, use a different inner diameter, or signifigantly slower speed rating.
(Also, you can buy tires online)