What's the meaning of The idom or slang cut "somebody in on .....".

[setsails]

I encountered a few sentences containing idoms or slangs that I can't understand while I was reading an article excerpted from the novel The Third Man (a thriller, witten by Graham Greene).although I have looked them up,I can't find the entries in the dictionaries. So I ask for help and expect to get the answers.

1. Martins - Were you going to cut me in on the spoils ?
Harry - I've never kept you out of anything,old man ,yet.

2. Martins - Couldn't you stuck to tyres ?
Harry - Like Cooler ? No,I've always been ambitious.

3.

[Gillnetter]

I encountered a few sentences containing idoms or slangs that I can't understand while I was reading an article excerpted from the novel The Third Man (a thriller, witten by Graham Greene).although I have looked them up,I can't find the entries in the dictionaries. So I ask for help and expect (Impolite use of the word. A military officer or a manager may expect to get an answer - one learning is hoping to get an answer.) to get the answers.

1. Martins - Were you going to cut me in on the spoils ?
Harry - I've never kept you out of anything,old man ,yet.
Cut me in on the spoils - Give me some of the money (gold, silver, or any other valuable thing) obtained by less than honest means.
2. Martins - Couldn't you stuck to tyres ?
Harry - Like Cooler ? No,I've always been ambitious.
I'm not familiar with this expression but it sounds as though he is asking why the other one did not stay with what he had been doing. If someone is ambitious he will probably try different things to succeed.
3.

Gil

[setsails]

Hi,Gillnetter! I'm setsails. I'm really glad that my question has been answered. And I'm really thankful for your correction to my impolite use of the expression expect to get the answer.

[Johnny Alpha]

Hello, interesting question. I hope you find these answers edifying.

1. Martins - Were you going to cut me in on the spoils ?
Harry - I've never kept you out of anything,old man ,yet.

The slang 'cut' in this sense relates to pushing through an obstruction, e.g: "he cut through the crowd". To 'cut some one in' is to make a space for them around a table, for instance. To 'cut in' on a dance is to interrupt a couple and take the partner, in order to continue dancing with them.

2. Martins - Couldn't you (have) stuck to tyres ?
Harry - Like Cooler ? No,I've always been ambitious.

Harry Limes was a black-marketeer, and his illicit activities included trading car tyres, as well as petrol (gas) and saccharine. The theft and resale of penicillin was far more lucrative, and malign, than anything he'd done before.

[Kathleen Shuster]

"Cut you in" means giving you a part of the money.