After I have installed this tray can I tile straight on top of it or do I need to create a gradient with my tiling?
You can tile straight on top of the tray, it is reinforced with material that connects to tile adhesive very well.
Gradient is already premachined, in case of this tray the slopes are from every corner of the board to every corner of the tray.
It's crucial to cut your tiles according to the slope of the tray. You will need to diagonal cuts to match tiles shape to the slope. Please check Technical Drawing tab on the product page to see the slopes.
I will be happy to answer any more of your questions.
David 020 7193 0953