I think this has nothing to do with tyres, but the vehicle itself. ie. suspension and shocks, joints etc.
I wonder what long term consequences are there if I carry above the maximum load limit on a daily basis, which is very likely for me. Of all points, I missed out this point when hunting for a car.

Most Jap cars of similar capacity has at least a 400kg laden weight limit.
Even a cheap, bottom of the range 800cc Chery QQ has a 405kg laden weight limit.
I think there must be something wrong with the Latio?

And the safety of Latio owners are of serious concern too.
As most Latio on the road are only 3 years old, no one can guarantee that few years down the road, when most Latios get older, the problems due to the low laden load limit of 305kg will surface?
Toyota Vios 1.5 - 410kg laden weight
Maximum Laden Weight : 1505 kg
Unladen Weight : 1095 kg
Mitsubishi Lancer GLX 1.6 - 438kg laden weight
Maximum Laden Weight : 1600 kg
Unladen Weight : 1162 kg
Hyundai Getz 1.4 - 485kg laden weight
Maximum Laden Weight : 1540 kg
Unladen Weight : 1055 kg
Perodua Kelisa 1.0 - 399kg laden weight
Maximum Laden Weight : 1200 kg
Unladen Weight : 801 kg
Chery QQ 0.8 - 405kg laden weight
Maximum Laden Weight : 1285 kg
Unladen Weight : 880 kg