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# wheels

An array of [`SCNPhysicsVehicleWheel`](/documentation/SceneKit/SCNPhysicsVehicleWheel) objects representing the vehicle’s wheels.

```
var wheels: [SCNPhysicsVehicleWheel] { get }
```

## Discussion

You can dynamically change the suspension and traction properties of a wheel connected to the vehicle by using the corresponding [`SCNPhysicsVehicleWheel`](/documentation/SceneKit/SCNPhysicsVehicleWheel) object or by using [Key-value coding](https://developer.apple.com/library/archive/documentation/General/Conceptual/DevPedia-CocoaCore/KeyValueCoding.html#//apple_ref/doc/uid/TP40008195-CH25) with a keypath of the form `wheels[index].propertyName`. For example, the following code changes the size of the first wheel attached to the vehicle, simulating a failed tire:

```objc
SCNPhysicsVehicle *vehicle = [SCNPhysicsVehicle vehicleWithChassisBody:car wheels:wheels];
[vehicle setValue:@0.1 forKeyPath:@"wheels[0].radius"];
```

---

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