Automotive Technology/Tire Code

Tread width is usually in millimeters
The aspect ratio is the sidewall divided by the tread width expressed as a percentage.
They don't make passenger tires in the US that aren't radial.
Rim size is usually in inches for unknown reasons.
The load index refers to how much the weight the tire can handle
The speed rating, shown as speed symbol, gives a maximum speed tolerance of the tire
DOT tire code is a four digit code, 2 digit week and 2 digit year

The higher the aspect ratio, the easier the tire comes off the rim.