This is the width of the tires in millimeters once mounted & inflated.
Aspect ratio is the sidewall height. This number is a percent of the width.
This indicates the rim size.
The offset of a wheel is the distance from the hub mounting surface to the center line of the wheel. The wheel offset is measured in millimeters and results in a positive, negative, or zero offset. Positive offset is when the hub mounting surface is toward the front or wheel side of the wheel. It is common to find a positive offset in newer and front wheel drive vehicles. Negative offset is when the hub mounting surface is toward the back or brake side of the wheels centerline. A negative offset wheel usually has a "deep lip." Zero offset is when the hub mounting surface is even with the centerline of the wheel.