How to read a friction circle or G-G plot
A friction circle is just a map of the car’s G forces. Braking goes one way, acceleration goes the other, and left and right turns spread out to the sides. The useful part is seeing where one lap reaches the outside of that shape and another stays tucked inside.
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The main idea
Points farther from the center mean the car was accelerating harder in some direction. When the faster lap reaches outside the slower lap in one area, find those points on the track and look at that section.
What to look at
- The outer envelope in each direction
- Empty or lightly used transition regions
- Asymmetry between left and right turns
- Clusters tied to specific track locations
Try this
- Use correctly oriented and scaled acceleration channels
- Build the plot from clean comparable laps
- Color or select points by track position when possible
- Compare envelope and transitions between laps
- Return to time traces and video for context
Keep in mind
The shape is not a perfect map of the tire’s limit. Banking, aero, bumps, setup, and sensor behavior all bend it around.
FAQ
Why is the plot not circular?
Cars often brake, accelerate, and corner at different capabilities, and track and sensor effects create asymmetry.
Can an empty area prove unused grip?
It suggests the dataset did not record that acceleration combination. It does not prove the combination was safely available in that corner.