No, do not increase or change your tire size without consulting the SC or BMW expert first.
If not mistaken BMW got speed/tire sensor which is program to match the original tire size.
If detected bigger or smaller size diameter it may come out error code or tire warning sign.
If you think current tries is not suitable, just venture to other brands or model but maintain the original size if possible.

Your steering having the clunking noise when turning? There's a repair kit for that, around 400 bucks including installation
As long as the tire circumference difference between the front and back tires is not too big, it will be fine.

It sounds like some spring sound. Still under warranty can claim?
I heard steering noise is a known issue for F30s

Yea I am waiting for the end of warranty inspection. I hve issues with my transmission. It jerks at D2 and around D4/D5.

Is their inspection trustworthy ? Or they will just com3 back  and say nothing wrong

Is it normal when you slow down, the gear downshift and you can feel each downshift? Like the RPM will jump each time the car shift gear..

Normal

Everytime it downshifts, at each change of gear, it will rev up by itself..

Normal AT cars don't do that right ?

I notice even on flat roads, when brake and slow down, the car will downshift and each downshift the RPM will rev to 1500-1800. So sometimes you can feel the rev, it feels like a pullback. This normal too?