I will say that I had issues with my 614's back in 2012.. they were 4 year od tires with the date codes of 08... I replaced all with 2012 date codes..
When its time to swap these out , I too will look at the Sailun S637 tires..
Our company started dealing with Schrader International as a supplier of material... they carry their TS cert... Because of that , they cannot purchase from US unless we are ISO 9001 at a minimum ..
They would not place the orders until their quality team came to our facility and did a quality audit..
It the Sailuns are made the same way , I will consider them at that time . .