Beware the offset and it's effects. Why not get the correct specification as fitted already? All the markings are on the wheel? Also remember the potential insurance implication of not fitting correct equipment.
Notes on offset;
The offset, measured in millimeters, can be negative or positive, and is the distance from the hub-mounting surface to the rim's true centerline. A positive offset means the hub-mounting surface is closer to the outside edge of the wheel, i.e. the wheel wraps around the hub and brake hardware more deeply; a negative offset means the hub-mounting surface is closer to the inside edge of the wheel and wheel sticks outwards more than inwards.
When selecting aftermarket wheels, a wheel with too little positive offset will be closer to edge of the fender, and one with too much positive offset will tuck inside the fender and be closer to the suspension components. Wheel width, offset and tire size all determine the way a particular wheel/tire combination will work on a given car. Offset also affects the scrub radius of the steering and it is advisable to stay within the limits allowed by the vehicle manufacturer. Because wheel offset changes the lever-arm length between the center of the tire and the centerline of the steering knuckle, the way bumps, road imperfections and acceleration and braking forces are translated to steering torques (bump-steer, torque-steer, etc.) will change depending on wheel offset. Likewise, the wheel bearings will see increased thrust loads if the wheel centerline is moved away from the bearing centerline.
In other words using the stock wheel offset number as the starting point, a lower off set number makes the wheel stick out more and a with higher number it sticks out less. (Lower is out more, higher is in more.)
