we tried that already, its actully pretty cool, we were going to do all of them , then we went to a swap meet and found 8 old skool tires with the huge white wall for 100$ so we went that way, it really work tho
so i got a free tire today so tomorrow i think i may start grindin into it and ill post some pics, let you know how it turns out. if it works im gonna do all my tires
the main reason thay put that last layer of black on is to cover up the part of the white thay dont wont you to see. after i watched that video I went to work and looked at a rather old tire on the car parked next to me (it was raised letters) you could see the white strip under the black. Not very well but you could clearly see were the white strip was (was just as wide as the videos)
I've also hear of Lowrider guys "shaving" their white walls to make them fatter. I dunno how, but maybe U can look into that aswell. It could be easier.