Yes, 40th formula that works.
I would go to north pole for saying 40 PPM too confidently ....
Now back to topic :
I'm not sure WD40 is suitable tire enhancer for foam tires.... I think paragon or jack the gripper are the correct tire enhancer for foam tires.
BTW, I notice this situation : 1 month old used tires soaked with paragon, the used tires wont match the grip of fresh new tires. 2ndly, I also notice, paragon makes foam tires inconsistent. The first 6 minutes get too much grip, and after 15 minutes the car start skating around. So I stop using paragon on foam tires ( unless if I feel I need to ). Normally I open new set of tires and enjoy the day.