They would be grade 316 Stainless steel collared eye bolts ( not eye NUTS.. be careful!!)
The best thing with 316 stainless steel is the harder you pull on it, as it begins to deform it gets HARDER... so even if you bend it.. it's unlikely to break ( up to a certain point of course, that no towing action should ever reach!!)
I just found this information from one of our suppliers:
You guys are looking at the M10 eye nut (at the bottom of the page) so shows a WLL of 400Kgs ( with a 5:1 safety factor - so a theoretical limit of 2Tonne).
Cheers