[aerohead]

So, in order to stretch the battery 10%, you've got to do what you're already doing with 90% of the energy.
A 10% reduction in Road Load.
All aero.
All R-R.
Or, some combination of the two.
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The KIA EV6 GT-Line RWD is EPA COMB 310-miles range, compared to the IONIQ 5, at 256-miles.
The RWD has 235/55 R19 101H KUMHO Crugen HP71 EV ( M+S ), vs 255/45 R20 105V Michelin Primacy Tour A/S ( M+S ).
The narrower section has better aerodynamics, and I suspect a lower coefficient of power absorption.
Mercedes-Benz is using a 185mm section on their EQXX, range leading concept.
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In 2018, Robert Palin, at electrek.com, reported that the 19-inch Tesla Model 3 Aero Wheels were good for a 10% efficiency gain, and 5% higher range on the highway.
Since Hyundai/KIA/ Genesis all share the same mechanicals under the skin, you might be able to find a direct fit wheel, or wheel cover option, which along with a LRR tire, nearly gets you to your 10% range target.
If not, a small amount of streamlining ought to get you into the inzone.