Kia Soul EV 2020
I would have to say, consider this a warning! Going from 255 tyre to 225 width is a huge loss of contact patch and has substantial safety implications for such a heavy car: braking will be affected in unpredictable ways, including poor car balance when turning.As pointed out above, you have to change the width/height of the tyre. So 255/45/20 becomes 235/55/18 or even 225/60/17 if they’ll fit over the brakes (which they almost certainly will). That gives you a significantly narrower tyres and 1-1.5 extra inches of sidewall which is great for efficiency, ride comfort and stopping you kerbing your alloys.
Its not an issue in the UK but in some European countries (definitely Germany) they’ll only let you fit tyres with dimensions on the plate in the door.
If you are safe driver and not "racing", it might be ok, but still something to consider.
What size tyres are specified in the car's manual? If the specific tyre size, you are considering is not on that list, you have to think very carefully if you want to fit something like that on the car.