My car demands:
P205/55R16 89h
p is for passenger. (as opposed to truck, trailer, or m for motorcycle - yes they use the same format)
205 is section width in millimeters.
55 is “aspect ratio” or “profile”. I think: Ratio of width (along car axle) to height (along radius)
R is “radial construction”, most are radial - there's the rare D for “bias-ply” or B for “Belted”
16 is for wheel diameter, in inches. you might also find these in millimeters.
89H is for the service description; the service the tire can provide. the number is some factor with respect to weight rating, the letter is a speed rating. (H is 130mph)
| Speed Rating | Miles/Hour | KM/Hour | Typical Application(s) |
|---|---|---|---|
| L | 75 | 120 | Trailer tires |
| M | 81 | 130 | Spare tires |
| N | 87 | 140 | Spare tires |
| P | 93 | 150 | |
| Q | 99 | 160 | Select winter tires |
| R | 106 | 170 | Passenger and light truck tires |
| S | 112 | 180 | Passenger and light truck tires |
| T | 118 | 190 | Passenger and light truck tires |
| U | 124 | 200 | |
| H | 130 | 210 | Passenger sedans, coupes, SUV and CUV’s tires |
| V | 149 | 240 | Performance sedans, coupes, and sports cars tires |
| W | 168 | 270 | Performance sedans, coupes, SUV and CUV’s tires |
| Y | 186 | 300 | Exotic sports cars tires |
| Z | 149+ | 240+ | High-Performance vehicle tires |
there's a bunch of other shit but none of it matters. https://goodride-tires.com/decoding-tire-size-how-to-read-a-tire-sidewall.html