You can invite a friend to Truck Star by following the steps below:

Navigate to the "Leaderboard" section,

Go to the "Friends" tab,

Tap on the "Add Friends" button.

Scroll down to the "Find Friends" button and tap on it.

Tap on the "Invite Friends" button to choose share your request URL or invite friends within Messenger.

When your friends tap on the link, they will become your friends in Truck Star.