Camber action on on-road sponge tire
 

Observate long time about the camber on sponge tire, I feel its different than rubber racing slick. I can c from any race car like F1, WTCC, those camber determine by which side of the tire was used, too much camber the more wear inside or not enough camber the more wear on outside. The proper camber measured when how lean is the car in corner and ride hieght, and how large the camber is.

Ok, suppose the brand new sponge tire without truing, this is 0 camber on tire and give 3 degree on rear chassis, I've found take serveral laps to wear some of the of tire before the grip comes out. Even I realised it grip enough, but the tire told me its not enough camber, the inside weared much then outside.

Any idea why the sponge and rubber slick work in opposite way?

Is this your rx8?
The tire wear on 8th scale is huge compared to other classes.
So much power and down force coupled with overdrive drive chain.

Tires going to wear fast!

The slightest adjustment can turn wear dramatically from coning outward to coning inward. Best is when there is a slight coning inward, achieving dead flat wear on rears is almost impossible because of corners and the car's lateral load. The top rear arms and front castor setting have a lot to do with too.

blis
 

that is correct buddy i have observed the same thing and yes it is almost impossible to acheive dead flat wear.