help with trucking laws questions usa and canada

It's not meant to level out anything. I never measured the travel, but it might be around 2 inches.
You can make a slight slope for the water run off the roof but not more.

 

It is not common, but it is available. I have had it on trucks and trailers due to the fact I hauled a lot of oversized loads (buildings) that required blocking and to level them out.

 

grade 30 is not allowed, or I am told. I buy only grade 70 transport chains for my trucks. but it is really how it is used that matters and where it is used, someone else can step in.

I never saw a 1/4" grade 70, I start out with 3/8" only and have some up to a 1/2" for my heavy haul trucks.

BUT here is a link to a good chart that should explain the ratings to you -

Chain Strength Chart

 

Unmarked securement devices are not allowed in Canada. For marked devices the same WLL and use applies. Grade 70, 3/8" and 1/2" are most common and some guys carry a few lengths of 5/16" for securing small items or accessorial pieces of larger loads.

This is the chart contained in the Canadian regulations: