kcfm wrote: Well, like i said, with the goal of pushing the wheels out a bit to be more flush with the fenders....in order to do this, how much could I deviate from the stock offset of 40 without causing any harm?
Here's how I would go about achieving your goal...
Take a measurement now with your stock wheels; find out how far it is from the outside face of your factory wheels to the outside face of your fenders. Take this measurement for the front and for the rear. Now what you want to do is essential get the widest wheels you can for the diameter you are shopping in without going so wide that at stock offset you blow past the fender line (you don't want to drive a dune buggy, do you?). Assuming that even the widest wheels for the diameter don't bring the wheels flush to the fenders (easy calculation; for every half inch wider than stock the wheel is, at stock offset, the outside face is another quarter inch farther out), you can then look to compensate with some negative offset.
So, let's say, hypothetically, the stock wheels' outer faces sit 1.25" in from the fender face at the front and 1.75" in from the fender face at the rear. Why don't we set the goal for the wheels to be 1.25" farther out at the face? Okay, so let's say the stock wheels are 17.0x7.5; if we wanted to use stock offset wheels and get 1.25" farther out, we'd need....10" wide wheels. Okay, that's probably a bit on the overly wide side to find. I'm thinking some 20x8.5 wheels are pretty doable, though, or maybe even 21x9. So if we go for 9" wide rims, we'd need another half inch out; +30mm offset would get you flush at the front and 1/4" in at the rear. If you're doing 8.5" wide rims, you'd want maybe +25mm offset.
Be careful as certain offsets tend to be more popular than others. Common offsets you'll find are about +15mm for, "rear wheel drive wheels," and front or all wheel drive wheels tend more to be in the +30mm to +45mm range. Figures in the 20s are harder to find.
Going too low won't cause terrible amounts of harm, I don't suppose, but I've never gone so low that I've experienced premature wheel bearing wear. I just know that is said to be the primary stress- or reliability-related issue with excessively low offset compared to stock.
-Ed