Reckless Racer — ruling 1

This is a triggered ability, not an activated ability. It doesn’t allow you to tap Reckless Racer whenever you want; rather, you need some other way of tapping it, such as by attacking or crewing a Vehicle.

Reckless Racer — ruling 2

For the ability to trigger, Reckless Racer has to actually change from untapped to tapped. If an effect attempts to tap it, but it was already tapped at the time, this ability won’t trigger.

Reckless Racer : règles, fonctionnement et interactions (MTG)

Reckless Racer is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

First strike Whenever this creature becomes tapped, you may discard a card. If you do, draw a card.

How it works : Reckless Racer

Original English text — Wizards of the Coast / Scryfall

#1February 9, 2017· Wizards of the Coast
This is a triggered ability, not an activated ability. It doesn’t allow you to tap Reckless Racer whenever you want; rather, you need some other way of tapping it, such as by attacking or crewing a Vehicle.
No other card is named in this ruling.
#2February 9, 2017· Wizards of the Coast
For the ability to trigger, Reckless Racer has to actually change from untapped to tapped. If an effect attempts to tap it, but it was already tapped at the time, this ability won’t trigger.
No other card is named in this ruling.