News to me too, and I have always wondered where it came from. My first knowledge of it was at Midlands Storage when they picked up a contract for carrying low height but heavy goods and I asked what was going on when I saw a flat trailer being converted to 2 feet high steel railings all around it and was told that a sheet was being made specially and that it was called a tilt. Couldn’t work out why, and still can’t.
I will resist any temptation to tilt at windmills by guessing, so nope, no idea here of the origins of “tilt”.
Doesn’t ‘tilt’ originate from either the dutch language or a dutch manufacturer?
But you have to admit our way is easy. 
No offence was taken by me, as my lack of spelling and grammar I put down to my lack of sticking in at school as i skived and left school as soon as I could and been in work for 40 odd years, so it doesn’t hud yea back