How to Determine the Ball Size of a Coupler

A correct size hitch ball keeps a trailer attached to the tow vehicle.

It is important to have a proper fit between a towing ball and the trailer coupler while towing the trailer. Most trailer couplers have the size stamped on the flat top portion of the trailer tongue, but sometimes the stamped size is missing, obscured by years of corrosion or covered by paint. When the numbers are missing or unreadable, you need to determine the correct size of the coupler before connecting the coupler to a hitch ball.

Things You'll Need

• Two wheel chocks
• Tape measure

Instructions

1. Place one wheel chock in front of a trailer tire and one wheel chock behind the same tire.

2. Turn the crank handle clockwise to raise the trailer tongue to a comfortable working height.

3. Set the end of a tape measure on the inside edge of the coupler wall. Pull the tape measure across the coupler opening until you reach the other side of the coupler wall.

4. Compare the measurement to a trailer ball chart. Select the smallest trailer ball nearest the exact size of the coupler to ensure a tight fit between the two components.

References

• BuyAutoTruckAccessories.com: Guide to Towing
• Automotive Accessories Connection: Trailer Hitch Balls, Mounts And Draw Bars