Yeah Cragar, and American Racing wheels still use that s*** for muscle cars...Get it out of here...
Backspacing/offset is fixed per wheel...You can sometimes increase it by machining the wheel hub surface down, or decrease it by using wheel spacers, both of which cannot always be done...with variables including wheel strength and stud length...
As far as offset:
It refers to the inner portion of the hub's (the surface that mounts on your brake rotor or drum hub) distance from the center of the wheel (placing the wheel vertical on the ground as if mounted on a car; the middle line of where the tire will stretch over...the middle section of a 8" wide wheel would be 4"s in from the outer lip) Most FWD require a + offset (measured in mm), in which the center mounting hub's surface is + "45" or + "50" mm from the centerline of the wheel...those crazy Germans will mount discustingly wide 11" wheels on the back of Porsche Turbo's with NEGATIVE offsets, sometimes as much as -10mm, which results in huge machined lips or "deep" dish wheels...that obviously will not fit on any Protege...
For reference, Stock P5's have a wheel offset of +50mm on the stock 16x6" wheels...also with a bolt pattern/spacing of 5x114.3mm