Screw-in towing eye, size of

[electronpusher]

Just got a Vauxhall Astra (2015). The kit in the boot has a chunky towing eye with a big screw thread. I tried it in the sockets both ends of the car and... pretty sure it's too big. Certainly it's not just going in.

Looks like it has been this way since new - repair kit in the no-spare-tyre well looks untouched.

What are the standards & how do I get one?

(as I write, I'm thinking the answer is to go to the dealer and ask... but they're sure to want more money than I think is fair)

[CanAm]

It may be a left-handed thread. Seriously. Apologies if you were already turning it that way.

[electronpusher]

CanAm said:

It may be a left-handed thread. Seriously. Apologies if you were already turning it that way.

Exactly that, thank you.

To stop people using an M16 (or whatever it is) bolt instead?

Because it will unscrew under load if right-hand thread?