Absolute newbie question on new tires with wider look

[Pd.com]

So sorry, I am a newbie here, but also when it comes to performance upgrades in general.
I have a 2021 st with both trac and street packs. Replaced my tires about two years ago with another set of the stock Perelli’s.

have been reading here a few discussions about putting a wider tire on the stock rims. There seems to be alot discussion on whether a 9.5 inch tire will fit on a 9 inch rim and/or if it is safe or ok with insurance.

if I were to replace my original Perelli‘s with the same (but the weatheractive instead of the all season) What would the correct “oversized” tire specs be?

would this cause the tires to slightly stick out from the wheel well? think i may like that look

Would the size details translate the same to the Michelin pilot sport A/S?

and lastly, i see all these tires listed as 275/45/21. Then most have “110” after. Mine have “107”. What is this difference?

thank you so much to anyone who replies, sorry for the total newbie questions trying to learn!!

 

[UNBROKEN]

The biggest you can go on the oem 21 is a 295/40. It’s actually pretty popular and looks nice IMO.
The number is the load index…tells you how much weight the tire is rated to hold. The letter that usually follows is the speed rating.

 

[Robm]

I have a 21 ST loaded as well. I'm now on my second season with the Michelin's mentioned above in a 295/40/21. They're fantastic and look amazing. No issues at all.