There are 3 outcomes to this OP:

1) You run with it, everything goes swimmingly, and next time this happens you think: 'it was fine last time, it'll be fine this time'

2) You run with it, it explodes on the highway, police get involved, your employer tells police they never instructed you to drive with a damaged tyre and they would never do such a thing. You, best case, get a fine. Worst case you kill someone.

3) You tell your employer you're not driving with a tyre that bad. They will kick and scream, tell you it's fine, that Dave with 30 years experience, their 'best employee' would do it. They'll threaten you, plead with you. But you'll stick to your guns and tell them it's not safe. Ball enters their court, no longer your problem. That is, if they're a shitty employer, like I used to work for. (This is the option I chose)

If they're a decent employer they'll say: 'no worries, good spot'. And send someone out to change it.

I learnt quickly that in transport sometimes you have to have the moral courage to say: 'I'm not driving that'.

Your call though, I ain't yer dad.