I have installed Advan Db (195/65/15) from day one in my 1.6 altis, I was keeping 28 in all tyres for soft drive on bumps but after few weeks, i thought of putting 30psi in all tyres, to my surprise car became so light and believe me shifting of gears became so smoth. I could hardly feel any jerk of 4 speed auto. so from that day onwards, i always keep 30 or sometimes 31 as well.