My second eBike Build, Advice on tyres (tires)

Hello, I'm in the midst of my second eBike build - based on EEB Full Suspension E-Bike Frame, parts are on order from China (Em3ev);
Wheels are 19" motorcycle rims and width is 50mm (2") inner and 55mm outer.
I need advice and source of suitable road tyres (tires) - (mixed use , off road and on road would be ideal), inner tube and rim strips;
I'm not familiar with the tyre (tires) sizing terminology for motorcycles: I'm based in the UK and asked a couple of online stores for recommendation - but they simply ask for the tyre (tires) size - which doesn't help;
Advice and recommendation will be much appreciated - oh, speed rating J (62mph)

Thanks

This is what i need:

https://www.oponeo.co.uk/moto-tyre-details/continental-kks-10-2-50-19-45-j-m-c#224902851