This is a basic HOW TO GUIDE
Here's a good video for all the people needing help on how to measure spacers.
In order to determine new wheels and tires you can use the same information for fitment. For example, OEM wheels are 19x8.5 +50. If you measure 1" to the fender then you can fit a 25mm spacer and it would sit exactly where you measured the end of 1". For new wheels in 19x8.5 you could just buy one with the offset of +25 and it will sit exactly the same as the previously measured OEM wheel with spacers. Now to increase wheel size whether in width or size you can use an offset calculator and a tire size calulator. I use these two for quick and easy understanding of what to enter in the blocks.
Once you determine what size you want to go with make the outer clearance match your desired wheels with the fitment of your already measured out wheels, along with overall diameter of the tire size matching within 3%. Some examples for both are a 20x8.5+25 will match a 19x8.5+25 pair that up with a 245/35/20 tire and your wheel/tire may be bigger but the overall size is only a .03" difference in size. Keep in mind the front and rear of the vehicle can vary for clearance, caliper clearance of the new wheels, and our independent suspension allows the wheels to go inward as the suspension compresses not affecting the fenders. Also if you lower the vehicle and increase camber all this will have to be done over again. I would recommend lower the car first, then measure wheel clearance, purchase new wheels. If the new wheels don't have a 66.1 bore you will need hubcentric rings, also verify what lug nuts are required. Hopefully this helps.