Dear everybody-wanting-to-increase-height-of-the-vitz, different options seem to work but the best is in my view to simply change the springs to slightly stiffer and larger ones. I changed mine's rear springs only and despite carrying a cng cylinder, the car doesn't touch now, if i'm slow enough, even on the highest speed breakers. No need for diagonal crossings any more. Even on higher speeds, the actual cause of touching is that my front shock absorbers are soft - which I've kind'a gotten used to and don't want to change right away.
Other than that, storm's right on the dot on tyre/rim sizes. Just that I believe he meant 175/70R13 instead of 75R13. To add, 13" rims are much better for family cars (specially in pk) as the overall drive is softer too. I'd recommend 175/70R13 to everybody wanting to change tyres.
Btw, finally got my tyres changed. The older Falkens served really well. This time bought Yokohama Aspec A300 185/70R13 (searched for 175s but cudn't find them and really wanted to buy the A300s). So far they're great. But will know for sure after some more driving. Any recommended place for getting the wheels aligned in Isb? The few ones I checked out, didn't look very reliable. Thanks.