Means that the diameter is about 20", and the width of the tire is something similar to 1.75"
The stock tire size is P175/65R14 (or 175/65/14)
175-70-14
175/65R14
175/70r13
175/65/14
175/70R14 is stock size for the stand neon
175-65-r13
175/70/R13
175/80R13
stock is 175/65-14
The recommended tire size for the 1989 Toyota Corolla is 175 R70 13. However, a size larger can be used with no harm to the car.
Stock wheel size was 13". A 175/80/13 Closely resembles the stock tire size.