That’s because I’ve tested that in real life. There isn’t a formula that can calculate the difference between tires or how the tires are positioned on the rollers or how much load is on them when the car is strapped down.
What do you do about tire pressure with your formula?
The power loss of say my drag car with 14-32 tires and a stick is different from a car with street tires and a turbo 400.
Can you see that whatever formula you found while researching is flawed unless it covers all the minutiae?
If you have a formula I’d love to see it.
