first number is the width of tyre, if this number is bigger then your tyre will be wide and better road grip, if with is small then road grip will be less but you will get better acceleration.
second number is the height of tyre wall from bottom to RIM outer side. It only tells tyre is low profile or otherwise.
third number is the rim Size, if rim size if bigger then your car will look cool and if rim size is small then you will get smoother drive.
195/55/15,195/60l15 or 205/55/15 all three have quite wide tyre size which mean you will have better road grip, but slower acceleration. I recommend that you should not go above 195 otherwise you will notice difference in acceleration.
Best one for City drive is 155 or 165 and off road/hilly areas is 185 or 195