Fix offset sign.

Author: D8H

examples/3d-car-coin-hunt/3d-car-coin-hunt.json

@@ -1789,8 +1789,8 @@
               "gearRatio4": 1,
               "gearRatio5": 0.74,
               "gearRatio6": 0,
-              "backWheelOffsetX": 6,
-              "frontWheelOffsetX": 5,
+              "backWheelOffsetX": -6,
+              "frontWheelOffsetX": -5,
               "wheelOffsetY": 0,
               "wheelOffsetZ": 0,
               "wheelRadius": 6,