improve corner handling, but accelerate slower.
look better, but the tire will cause you more.
give you better grip on the road, but will increase consumption.
So to minimize the cons, pick smaller offset, lighter wheels and narrower tires.
The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types (measured in millimeters). Backspacing, similar to offset, is the distance from the hub mounting surface to the inside lip of the wheel (measured in inches).
J is the width of the rim
You may also need to know the PCD, Stepwgn takes 114.3
number of holes, stepwgn takes 5 holes
sometimes, you will also need to know the thickness of the hub. As your screw may not be long enough.