---
title: "init(chassisBody:wheels:)"
framework: scenekit
role: symbol
role_heading: Initializer
path: "scenekit/scnphysicsvehicle/init(chassisbody:wheels:)"
---

# init(chassisBody:wheels:)

Creates a vehicle behavior.

## Declaration

```swift
convenience init(chassisBody: SCNPhysicsBody, wheels: [SCNPhysicsVehicleWheel])
```

## Parameters

- `chassisBody`: A physics body to serve as the vehicle’s chassis.
- `wheels`: An array of doc://com.apple.scenekit/documentation/SceneKit/SCNPhysicsVehicleWheel objects representing the vehicle’s wheels. A vehicle must have at least one wheel.

## Return Value

Return Value A new vehicle behavior.

## Discussion

Discussion Each object in the wheels array associates a node with the wheel to serve as its visual representation and defines properties for the wheel’s physical characteristics. Each wheel object must reference a unique node, which should be a child of the node containing the physics body used for the vehicle’s chassis. Typically, you load a node hierarchy representing the vehicle and all of its wheels from a scene file and then designate which nodes serve as the body and wheels. For a behavior to take effect, you must add it to the physics simulation by calling the addBehavior(_:) method on your scene’s SCNPhysicsWorld object.