Even though you're not changing the track width by replacing the knuckle, it's still a good idea to determine the best backspacing before ordering your new wheels. An easy way to measure is by putting the original wheel against a flat wall and measure from the center (inner mounting surface) of the wheel. Then using a long ruler or a straight flat piece of material, determine how many inches your wheel is spaced from the back lip of the rim to the center. This will give you a good idea of how far your new aftermarket wheels may stick out and also guide you when determining a new tire size. A lot of the time the more you can keep the tire inside of the fenderwell the bigger the tire you can fit onto the vehicle.