hi,

my tyre is 175/50/r15 on 6jj rims. currently i inflate at 220kpa.

i noticed that my tyres start to wear at the sides both left and right.

i noticed it happen after i inflate my tyre according to the car specification. before this the tyre shop do it. i didnt know what is the correct pressure needed.

can somebody help?

whack corners very hard? consider 230kpa/or around 32psi

and by sides you mean the outer side (not inner) of the tires on both left/right (driver/passenger) wheels?
if so, consider slight negative camber alignment (-1 to -2)

both front tyre, inner and outer side.

Savvy user eh

if its both inner/outer side, probably just under inflate and shouldn't be alignment issues (assuming both the inner/outer side of both tires are having "even" accelerated wear)

yup