Lexus SC 430 2001 Owner's Manual page 301

Installing spare tire
Install the compact spare tire and loosely tighten each nut by
hand to approximately the same amount.
Disc wheel
Disc wheel sheet
Nuts
Tapered portion
Tire jack handle
5-2. Steps to take in an emergency
Remove any dirt or foreign matter
from the wheel contact surface.
If foreign matter is on the wheel
contact surface, the nuts may
loosen while the vehicle is in
motion, and the tire may come off
the vehicle.
Tighten the nuts until the tapered
portion comes into loose contact
with the disc wheel sheet.
Lower the vehicle.
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