Group Pivot Point with P2 Gravity

[Marzipan151]

Hi all, very new to Phaser and I'm trying to basically make a colour switch kind of game. So I am using p2 physics for the rotating arcs so I can add collision detection later. I had these arcs as graphics in the game but then couldn't add physics to them so they are now sprites in a group call wheel. I have the pivot point of the group set to (85,85). I don't know why but this number works, the sprites are 170x170 but when I try to give the group a pivot point such as (0.5,0.5) it doesn't work I've even tried (0.25,0.25) to try and recreate the (85,85) pivot point. I am trying to do this because when I apply the p2 gravity to the game the wheels pivot point does not move so the wheels rotation gets bigger and bigger. If anyone has a possible solution to this or an alternative method to go about this then please reply! I'm so desperate right now it's not even funny.