Four Wheel Drive Robot Chassis Ratio of Length to Width

So i am at the design phase of a four (Normal) wheel drive robot, I have motors/gearbox. 60mm dia wheels and electrotonic etc.
The robot is going to be autonomous with a GPS receiver so i can tell it to GoTo lat/long and it will try to navigate to that place.
Question is before i start cutting and 3D printing is there an ideal ratio of wheel location width/length ratio.
Obviously if I make it VERY long and narrow it is going to have problems rotating on the spot.
So how far can the chassis design be out of square before i can expect turning on the spot issue.
Many thanks in advance imk

@imk Honestly good question and don’t have an equation to provide unfortunately.
Aside from military contractors, not sure how many companies of small robots actually calculate the ratio needed since quite a lot is involved:

  • Radius of the wheels
  • Distance between the wheels both front and back
  • Surface (for friction estimates) and wheel material (assuming rubber?)
  • Torque of each motor and if there are one or two motors per side
  • Turning radius (or turning on the spot and it sounds)

Fundamentally though, the closer the wheels are to each other, the easier it is to make a zero radius turn since the torque acting sideways on each wheel will be less (distance between center of rotation and wheel, and the force acting on the wheel). Therefore a very wide 4WD robot should be able to turn easily, but might have other issues.