Vehicles change friction and friction per material ?

How i can change the vehicle wheels friction ?

A. No function to change the friction and properties at runtime ?
B. No class or vars for physical material ?
C. How change the friction by material ? Using the material friction affects to the vehicle tires friction in what way ?

Check out the trace tutorials - like the one’s for footsteps. They show you how to create physics materials which have different characteristics (footsteps make different sounds based on the material) and can be used in BP. Might be helpful, might not. There’s a bunch on youtube.