Posi trac

[beemerten]

I dont know if i understand correctly how the posi trac works.
I got a 70 firebird 400,and when i spin the tires sometimes the right wheel set slightly less marks then the left one. I guess this depends on the surface,but is it possible that even with posi trac the two tires can spin at the same time but with different speeds?

 

[melsg5]

doubtful it's much of a different speed unless the posi is wearing out but in addition to surface variation you may have tire pressure differences and wear differences on the tires

 

[beemerten]

Thanks for your answer. I guess i should check my tire pressure then. It is very little difference but i was just curios about what could cause this.