I’ve seen both used in calculators for maximum pushing power (cof*weight), and just thought I should know which is correct.
Static friction is probably what you want- the wheels don’t normally slip when driving.
I’m talking about in a pushing war, when they should be slipping
When you are at maximum pushing power, the wheels are on the verge of slipping, but not yet slipping. Static coefficient of friction applies here.
Once the wheels slip, then you lose traction and the kinetic coefficient of friction applies. This is your new maximum pushing power until you regain traction.
So it depends on exactly what scenario you want to estimate.
Pure wheel rolling involves only static friction.