The difference between the 7" stock wheel and the 8" wheel you are trying to use is that they both have the same(or nearly) backspace, so with the 8" wheel the total difference is on all the outside half of the wheel, 1" wider. Since the rotor, caliper and wheel pivot around the line drawn through both upper and lower ball joints, that means the outside lip of the wheel swings in a larger arc when steered from lock to lock. The 8" wheel would fit just fine with a 4.25" to about 5" backspace, which would put the added width mostly, or all, on the inside half of the wheel.
The '83 Monte SS my mom had was 15 x 7" factory Sport wheel that looked almost identical to the 14" wheel you currently have on the Elky, just the colors are reversed, wheel is silver with black accents around the shaped holes. They were 3.5" backspace IIRC which is perfect with a 7" wheel. It had 215-60/15 Goodyear Eagle GT's on it from the factory, and Eagles tend to run shorter on sidewall height compared to other brands the same size we put on later in the cars life.
You might get the 8" wheels with too little backspace to fit but it will take a low profile tire to do it - 215-60 or 205-55, 215-55.
You size problem with 8" wheels without enough offset is common to most GM cars, my '72 Nova will not take an 8.5" wheel unless the backspace is 5", which leaves 3.5" on the outside half of the wheel. ....Recognize that familiar 3.5"-ish dimension again?
Last edited by ericnova72; 05-22-2010 at 08:25 PM.