The short answer

Use load stops to prevent lateral drift, not to carry a load through an unapproved point. Position them for the cargo shape and the rack maker’s bar limits, then use separate straps over the load. The stop should not press a sharp edge into a kayak, board, box, or roof.

Plan the layout

Item Check Failure mode
Bar engagement Stop and tower sit within the allowed area Hardware is near an unsupported end.
Cargo shape Contact is broad and stable Stop touches a point or fragile surface.
Strap path Strap remains flat and centered Stop traps or twists the strap.
Roof clearance Load clears roof and hatch Pressure transfers to the vehicle.
End protection Caps and edges are covered Cargo or strap rubs on metal.

Load the vehicle while parked, tighten only as instructed, and recheck after a short stop. Keep loose strap tails secured and use bow or stern lines when the carrier requires them.

Limits

This guide does not provide a load rating or universal stop position. The rack and cargo manufacturer instructions control.