I didn't want to post this here, since there is a vendor here...
But, this is a calculator that I found:
Tire Size Calculator - tire & wheel plus sizing
That was the basis of my plus-sizes I posted. Enter the stock size, plug in the desired width and profile, and you get a lot of info. Mostly what I looked at was radius comparisons. If those are very close, then the tire itself will be very close to stock, meaning you won't have much in how off your speedometer is, and it shouldn't "not" fit under the wheelwell.
My main thing is how the stock tires look like they're stretched over the rear wheels. I'll have to check the fronts to see what they look like, but, I don't like that stretched-on-rubber look.