Let's talk Scrub-radius.
If you mount a set of factory-diameter tires on factory wheels, at factory ride height, and
if you could draw a line thru the center of the Ball-joints, down to the roadway, and another line thru the center of the tires/wheels, as viewed from the front;
then, those two lines are, by design, supposed to intersect in the center of the contact patch. this is reduce tire wear from a thing called scrub radius, which occurs when the theoretical point wanders from it's design point. Normally, that point changes very little as the suspension cycles up and down from it's designed ride-height, but some change is unavoidable.
Now,
if you don't run the same diameter tire as was stock, and/or you don't run a stock zero-offset wheel, then you get into a situation where the two lines no longer intersect in the center of the contact patch. This causes the front end to, in a straight line, wander back and fourth, especially so in the depressed parts of asphalt roads, which can be very annoying, even on short rides.
So then, if/when you change your tire diameter from stock, or the offset from zero; then you have to manipulate the offset, to restore the patch back to or very close to, the intersecting point.
By experience,
I have found that 1/4 inch is acceptable, 3/4s is not, and 1/2 I don't like it at all, but in a City-car, I'll put up with it for a sharp set of wheels, going to car shows and such.
On a City-car, or one not your DD, this is not that big a deal. But on long trips, the constant wander, even on a concrete hiway, is tiresome. Combine that with a worn steering system, and it gets to be downright aggravating.
Finally, the point;
7s are actually 8inches outside to outside. That means the backspace will need to be 4 inches, on a stock diameter tire; more on a taller tire
Four inches is already pushing the envelope for Ball-Joint clearance with 14s. Even 15s will be close to rubbing.
At 4.5 inches backspace, I can guarantee you that even a 15 will hit the UBJ .
At 4.25, you will not be able to run the wheel-weight in the standard location on 15" steel wheels. and forget 14s
Like I said, 14s with 4" backspace is really pushing it.
To find out how much more you can run, just install a bare 14" steel wheel, put a jack under the K-member, back off the T-bar, then cycle the suspension up and down to find the minimum clearance to the BJ, with the wheel in the straight ahead position. Next, at that ride height, turn the steering wheel back and forth to find the tightest clearance. Next put a bottle-jack under the wheel, and jack the wheel into the BJ, so as to eliminate the wheel-bearing clearance. Finally, measure your clearance.
Now, remove the bottle jack, and the wheel, and measure the backspace on your test-wheel, then add the minimum clearance that you just measured, then subtract 1/2 inch for the wheel weights. The number you get, is the MAXIMUM backspace..
Double it to get the maximum physical wheel-size that you can run, on a same diameter as the test-wheel. From that, subtract One inch, to get the branded width of the rim.
My guess is that you will end up with a maximum backspace of 3.5> 3.75. Which means a branded rim of 7>7.5, to run a factory diameter tire with zero scrub, and a minimum BJ clearance.
All this to tell you, that, you may have to run the stockers up front, and something else in the rear. I see you have room in the back for 275/50-15s....... Maybe even 295/50-15s, lol.
I happen to have a set of small-pattern rally wheels that you might like; 14 x (I think) 5.5@ zero offset for the front, and 15 x 8s at near zero offset for the back. all need freshening. I'd have to dig them out to measure.
I'm pretty sure I could scare up a set of ET-IIs as well. Those are the kidney-slot style. I think I have a set around 14x7inches, and a pair of 14x8s
.
