Tire Width:
This measures the distance from one sidewall to the other sidewall in millimeters.
Aspect Ratio:
This is gotten by dividing the cross-sectional height by the cross-sectional width. It is expressed as a percentage and is directly proportional to the size of the sidewall.
Construction:
Basically, how the fibers are arranged. R stands for radially, D for diagonally, and B stands for Belted Bias-ply tire.
Wheel Diameter:
The distance from one end of the rim to the other.