The 9x3.00-6 tyre is typically the factory fitted tyre on models of Bolzzen Commando 4818 (blue/black dual 600w) and is factory size on Teverun Blade Mini and Kintech Venom 9 series.
Supports 6" rims where clearance does not support the more common, higher profile tyre such as 80/65-6 (10x3) due to clearance issues with fenders, suspension, callipers etc.
With the introduction of the CST 9x2.50-6, often that tyre is used in lieu of this tyre. Potentially as is the CST 9.5x2.50.
If requiring tube, being a relatively uncommon size, eSN recommends using a 9x2" tube.
Regarding Bolzzen Commando, (blue/black TNE models) with 4818 model (2x600w motors) using a 9x3.00-6 tyre this tube is a much better option than 10x2-2.5" tubes. Also suitable for use with CST 9x2.50-6 Road Tyre [CM560] which is considered a better tyre than the stock 9x3.00-6. This tube can be also fitted with 10" tyres can be fitted with fender spacers similar to the TurboTight NAMI Klima Fender Spacer Kit. The Elite model (4823.4 with 2x1000w motors) has factory fitted 10" tyres due to presence of factory fitted fender spacers as shown below: