How come no one seems to mix aspect ratios to maintain stock tire diameters when using staggered widths?

For example my sedan uses a 215/55/17 as a stock tire it has a diameter of 26.3 inches

Most seem to use a 245/45/18 and 275/45/18

I understand about wanting to fill out the wheel opening.

Now a 245/45/18 is 26.7 inches or 1.3% larger not a big deal, but then go onto the rear with a 275/45/18 and the diameter is now 27.8 or 5.5% larger then stock.

And the difference between the 245/45 and 275/45 is 4.2 %


Let’s now take a 245/45/18 and a 275/40/18 the tire diameter is 26.7 for both front and rear, and only 1.3% larger

Or a 235/45/18 and a 265/40/18 this would give tire diameter that is the same size as the stocks at 26.3

 

If you have a coupe, the fronts and rears have different size diameters as well as widths, which usually correspond to matching aspect ratios. On a sedan they use the same size so if you wanted to stagger the widths, you would have to change the aspect ratios to make the diameters similar. Thats why people don't use different aspect ratios on the coupe. In some cases though it is necessary, especially if you are going much wider in the rear