Our friend Andrew from Car Cam Central recently released this video about how to pick a Micro SD card for your camera. The Micro SD card is the biggest point of failure with dashcams and are often overlooked despite how problematic they can be for the user. Dashcams are particularly hard on memory cards due to the constant loop recording and heat which put significantly more stress on the card compared to a smartphone or traditional digital camera.
Andrew's video helps to explain why card speed isn't the most important thing to look for, nowadays most Micro SD cards are already Class 10 and a fast card can be had for cheap. Adding to Andrew's video though, card speed ratings are typically only their fastest possible speed and many manufacturers don't mention the minimum or average speeds which are very important for optimal performance. The memory controller and construction of the card affect compatibility and durability so are of utmost importance when researching memory cards.
Different dashcam manufacturers build their firmware and processors around specific cards so a card that works well with one camera doesn't necessarily work well with a different model. That being said the Transcend and Lexar cards Andrew recommends have worked well for us in a wide range of dashcams including Blackvue, Street Guardian and Thinkware. Some manufacturers do offer their own OEM branded cards such as Blackvue and Thinkware and while they are generally manufactured by familiar memory card manufacturers, their memory controllers are designed specifically to work with their dashcams and are the best for troubleshooting recording related issues with the camera.