How are you tieing down your car in your enclosed trailer

nm9stheham said
I know you won't like to hear this, but that is incorrect. The force is constant throughout the whole length, regardless of the length. There is no such things as load-spreading along a lengthwise support, loaded at the ends. (1st semester mechanical engineering.)

And if you have both straps or chains straight back, if one breaks, then the other cannot become slack if the restraints at the other end are tight. Del has it 100% right.

That assumes a rigid (no stretch) attachment like a chain or a bar. Straps are not rigid and have stretch. Therefore, they spread the load as the strap stretches with acute load changes and return to original tension if they have appropriate elasticity.