Toyota Highlander Hybrid 2013 Manual page 268

2-5. Driving information
Selecting trailer ball
Use the correct trailer ball for your application.
268
Trailer ball load rating
Matches or exceeds the gross
trailer weight rating of the trailer.
Ball diameter
Matches the size of the trailer
coupler. Most
stamped with the required trailer
ball size.
Trailer Typical trailer ball
class size
IV
II and III
I
Shank length
Protrudes beyond the bottom of
the lock washer and nut by at
least 2 threads.
Shank diameter
Matches the ball mount hole
diameter size.
couplers are
2 5/16 in.
2 in.
1 7/8 in.