Its hard to say from the images, but here is an authentic example of your coin. What is the weight and measurement? EASTERN CELTS, DACHREITER TYPE AR Drachm OBVERSE: Celticized head of Zeus right REVERSE: Celticized horseman riding left; wheel of four spokes above Struck by the Skordoski in Syrmia, 2d Century BC 1.87g, 14mm OTA 188/2-3
It's within range and from what I can see, it looks authentic, but I'm by far no expert. I'll keep my fingers crossed and hope someone with more knowledge replies.
Here are my Kugelwangels from the Celts of the Danube Region. They are imitating Philip II Makedonwn. Yours looks and is sized very similar to mine, especially my first pic... Celtic Imitation Philip II AR Drachm Kugelwangel type- Agora auction Celtic Imitation Philip II drachm - pecunum auction
i bought this bronze one years ago as just a "barbarous Celtic" and didn't really know what it was until just recently.