Board Thread:Game Discussion/@comment-26249703-20160103210236/@comment-29014134-20161017140946

Actually that curbs are very useful in Time Trials because if you have 2 wheels on it, it's not counted as "off-track". Also in some tracks (ex. Laguna Seca) curbs gently goes in. Although you still got to be careful, these can ruin your 10 lap race..