# Calculate Rolling Resistance Experimentally

I am trying to calculate the exact rolling resistance ($$F_{rr}$$) of my car. The approach I am going with is a coastdown test at a low speed so no drag slows down the car. From there I am going to measure the speed of the car several times and find the acceleration and therefore $$F_{rr}$$. With the help of an online polynomial regression, I am going to find the function of $$F_{rr}$$.

However, I am not sure if my approach is correct and if the function that I am going to find is indeed capable to give me the $$F_{rr}$$ at higher speeds.

• If you're asking "Is high-speed rolling resistance the same as low-speed rolling resistance" I suggest you edit your question to make that the title. At the moment the title suggests you want to know how to do the calculation, but your last statement suggests you're worried about the applicability of your low-speed tests. Apr 19, 2019 at 19:18
• If you do perform the low-speed tests, be sure to do them in both directions along your chosen "level spot" -- that way, if it's not quite level in reality you'll be able to cancel out the effect. Apr 19, 2019 at 19:19
• Wind is vastly important. Having done that experiment on a rig with bicycle tires, yes it can give reasonable and repeatable results, but in a car you are also measuring bearing drag, wind, brake drag (yes it happens) and so on. Jan 1 at 7:26

After obtaining a mean value, compare it with $$F_{rr} = \mu W$$.
Where $$W$$ is the weight of the car and $$\mu$$ the static friction coefficient.