Why Does The Curt Flex Air Fifth Wheel Head Roll Forward When Inflating the Air Bag?

Updated 06/25/2026 | Published 06/16/2026

Products Featured in This Question

Curt Flex Air 5th Wheel Pin Box - Lippert Rhino - 21,000 lbs

(202)

$2172.54

Question:

I bought the curt 21000 flex king pin box hitch from you guys I would like to know if it can be used with the curt A20 21000 pound fifth wheel hitch?? Also I would like to know why when u put air in the air bag it rolls the fifth wheel head forward on the truck what is causing this? Thank you

asked by: brian w

Expert Reply:

Thanks for reaching out Brian, happy to help!

Yes, the CURT Flex Air Pin Box # LC65VR is compatible with the CURT A20 5th Wheel Hitch.

As for the hitch head, some movement is normal. As the air bag inflates, it changes the geometry of the pin box and can cause the king pin to sit at a slightly different angle in the hitch.

A few things I'd suggest:

Make sure the trailer is sitting level when setting the air pressure.

Inflate the air bag only until the yellow indicator is visible.

Overinflating the bag can cause excessive movement.

What fifth wheel are you towing with the Flex Air?

expert reply by: James D

Brian

6/25/2026

The curt a 20 slider fifth wheel is what I am using

James D.

6/25/2026

@Brian Ok cool, no issues with those two working together. As always reach out if you have any additional questions and we appreciate you choosing etrailer!