New Hyundai i20 delivered on summer tires – which winter tires / winter complete bikes

Hello everyone, I’m soon the owner of a new Hyundai i20 1.2 62 kw. Hopefully delivered at the end of October. It comes on aluminium rims with summer tires. The additional winter complete wheels were too expensive for me. I signed a vario financing agreement at sixt leasing. Now to the actual question… What would you recommend: Buy only winter tires and then pull on the aluminium rims or directly winter complete wheels. If complete wheels, then aluminum rims or steel rims? And a uf Which sizes do I have to pay attention to when ordering? I would like to get the wheels online.The following information is available for the summer wheels: Aluminium wheels 6.0 X 15 tyres 15 185 / 65 H Load capacity index 84 Can I take the same information for the winter bikes?