Lexus LX 470 1998 Owner's Manual page 229

DRIVING TIPS
2. Select the appropriate trailer ball to match or exceed the gross
trailer weight rating of the trailer. The trailer ball load rating should
be printed on the top of the ball.
32X004a
" 1 Trailer ball load rating
3 Shank length 4 Shank diameter
3. When mounted in the ball mount, the threaded ball shank must
protrude beyond the bottom of the lock washer and nut at least 2
threads. The trailer ball shank must be matched to the ball mount
hole diameter size.
212
2 Ball diameter
Matching trailer ball height to trailer coupler
height
No matter which class of tow hitch applies, for a safe trailer hookup,
the trailer ball setup on must be the proper height for the coupler on
the trailer.
32X003a
" 1 Coupler
2 Trailer ball