If your computer does not have Bluetooth (or when connecting from iPhone/iPad), run Numpad Connect to use both Numpad and Racing Wheel with zero latency over your local Wi-Fi network.
Extract the downloaded ZIP archive and run NumpadConnect.exe. (If Windows SmartScreen appears on first launch, click "More info → Run anyway".)
Ensure your phone and computer share the same router/network (works even if your desktop PC is connected to the router via Ethernet cable, or via phone Personal Hotspot).
Enter the 4-part COMPUTER IP address displayed on the PC window (e.g. 192.168.0.7) into the Numpad app on your phone and tap START.