Spare tire

[EVCar]

Here are the specs for front and rear. Only
Looked up the 20/21 on TireRack.com. A little bit different outside diameters. Not sure if this is acceptable:

This front/rear set fits your 2025 Lucid Gravity 265/50-20F 285/45-21R.

• Size:265/50R20 (Front)
• Service Description:111Y
• Load Range XL
• Max. Load= 2,403 lbs
• Max. psi= 50 psi
• LM1 Lucid, soundabsorber
• Eco Focus:EV Eco Focus tire technology emphasizes low rolling resistance, resulting in better fuel economy.
• Noise Reduction Technology
• Electric Vehicle Tuned
• UTQG:600 A A UTQG
• Max. Load:2,403 lbs
• Max. Inflation Pressure:50 psi
• Tread Depth:9.5/32"
• Tire Weight:36 lbs
• Rim Width Range:7.5-9.5"
• Meas. Rim Width:8.5"
• Sect. Width:10.9"
• Tread Width:8.4"
• Overall Diam.:30.2"
• Revs. Per Mile:687
• Country of Origin*:KR

• Size:285/45R21 (Rear)
• Service Description:113Y
• Load Range: XL
• Max. Load= 2,535 lbs
  Max. psi= 50 psi
• LM1 Lucid, soundabsorber
• Eco Focus:EV Eco Focus tire technology emphasizes low rolling resistance, resulting in better fuel economy.
• Noise Reduction Technology
• Electric Vehicle Tuned
• UTQG:600 A A UTQG
• Max. Load:2,535 lbs
• Max. Inflation Pressure:50 psi
• Tread Depth:9.5/32"
• Tire Weight:36 lbs
• Rim Width Range:9-10.5"
• Meas. Rim Width:9.5"
• Sect. Width:11"
• Tread Width:8.6"
• Overall Diam.:30.9"
• Revs. Per Mile:673
• Country of Origin*:KR

https://www.tirerack.com/tires/tires.jsp?tireMake=Hankook&tireModel=iON+evo+AS+SUV&frontTire=65YR0IH01AXL&rearTire=845YR1IH01AXL&vehicleSearch=true&fromCompare1=yes&autoMake=Lucid&autoYear=2025&autoModel=Gravity&autoModClar=265%2F50-20F%20285%2F45-21R

FWIW, off the cuff comment from a techs supervisor at the SC was that he saw no problem with the smaller wheels on the rear. But he wasn't 100% sure.