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

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.

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.

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.

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