Lexus RX 450h 2010 Owner's Manual page 283

2-5. Driving information
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Tow hitch receiver (if equipped)
Selecting a trailer ball
Use the correct trailer ball for your application.
282
A tow hitch receiver installed
under the rear bumper is rated for
weight that does not exceed the
vehicle's total towing weight.
Trailer ball load rating
Matches or exceeds the gross
trailer weight rating of the trailer.
Ball diameter
Matches the size of the trailer cou-
pler. Most couplers are stamped
with the required trailer ball size.
Shank length
Protrudes beyond the bottom of
the lock washer and nut at least 2
threads.
Shank diameter
Matches the ball mount hole diam-
eter size.