that's odd. I'm on swifts too and my tires are considered one size small but I don't notice the wheel gap as much:
How long have you had the springs?
Based on calculations from stock tire sizes:
You're about .7 inches shorter in diameter in the front and .9 inches in the back. Meaning if you ran spec tire sizes you'd be able to cover another .35 inch of wheel gap in the front and another .45 inch of wheel gap in the back with OEM sized tires*.
*based on nismo specs:
NISMO tire size: F-245/40R19 R-285/35R19
NISMO rims: F-19x 9.5+40 R-19x10.5+23
You can adjust the tires to match OEM and lose some wheel gap.