Unless the tires are the same low-resistance models on the Gemini's, you can subtract 5% loss just from tire design not including the additional loss from the Induction wheel being slightly heavier and less aerodynamic.
Actually neither the Continental ProContact RX tire that is standard on the 19" wheels with the Gemini covers or the Goodyear Eagle F1 tire that is standard on the 20" Induction wheels are LRR tires. The Continental ProContact RX is a Grand Touring All Season Tire, the Goodyear Eagle F1 is an Ultra High Performance All Season Tire.
The Tesla 20" Induction wheel is a very aerodynamic wheel design. The only negative is that the Induction wheels cost $2000 additional (for a set of four Induction wheels, tires) versus the standard 19" wheels, tires. That and the Induction wheel is flush with the side of the tire where it can easily be damaged by contacting a curb. When a Model Y equipped with a tow hitch is towing a trailer with three or more passengers in the Model Y the tow rating is lower than the 3500 lb tow rating with the 19" wheels or the 21" wheels (Performance Model Y.)
Anyway, here is the maths [sic]:
19" wheel (named the Apollo wheel in the Tesla Parts Catalog, aka Tesla Power Sport wheel on the TSportline site Model Y wheel information page) comes with Gemini wheel covers (similar to the Tesla Aero covers that come on the 18" wheels on the Model 3) wt. 29.6 lbs
Continental ProContact RX 245/45/R19 wt. 26 lbs
Total weight: 55.6 lbs (not sure if this includes the Gemini wheel covers)
20" Induction wheel wt. 31.55 lbs (1.95 lbs heavier than the 19" wheel)
Goodyear Eagle F1 255/40/R20: wt. 25 lbs (1 lbs lighter than the Continental ProContact RX tire)
Total weight: 56.55 lbs.
The 20" Induction wheel and tire combination is only 0.95 lbs heavier than the 19" wheel and tire combo (may or may not including the Gemini wheel covers.) If anything, the additional weight of the Gemini wheel covers will make the 19" wheel and tire combo slightly heavier.