45 and 50 series means the height of the sidewall, for example, 205/50R16, which means the height of the side wall is 50% of the width of tyre, also can said as the sidewall is 50% of 205, almost like 102.6 something like that.

Xm1 wont be near RM400, it will be somewhere below RM300 maybe? just stay away from NCT5, my uncle's camry change 4 tyres to NCT5, RM300 per tyre, profile is 215/60R14, pity for him and his son that know nuts about tyres and dont listen to my advice