the standard tyre size for sojoki kultaz is 155/80/R13, air pressure 28 ~ 30 psi maximum. if you have purchased the NEW tyres of same specs or 165/80/R13 there shall not be a problem.
Incase you have swapped from a tyre shop for used tyres with alloy rims, you need to do some exercise and dirty your hands. park the car over levelled surface in daylight physically inspect the tyres plus feel each tyre with hands around as if pampering a kitten any bulge or boil in used tyres causes such bumpy ride.
chacha jan if you are running on stock wheels correct me with the wheel size,