Hi Volks

I finally saved enough to change the stock wheels on my Bora to the Audi RS6 wheels that I always wanted.
However, it feels to me that the handling is not as sharp as before, i mean the response is a little slower now, the moment between me turning the steering wheel to the front of the car changing direction has become a tiny bit longer.

My stock wheels are 205/55 R16, the new wheels that I got now are 225/45 R18.
When I first drove the car with new wheels, the steering feels very light, then I found out the tyre shop pumped the tyres to a higher pressure then what's said on the fuel cap, so I let out some air. Should the tyre pressure be different with different tyre size? or should it remain the same? (very rarely do i carry any passengers or luggage)

Is this handling change normal? or is it just me thinking it's gone worse, while in fact it's the same? I thought changing to wider tyres makes the car handles better. Or is it just me expecting too much?