What is the biggest size tires that I can fit onto my 2015 Ford F-150 18 wheels?

I apologize if this may be a common question on forums, but I'm new to trucks and the answers vary so widely.
I own a 2015 Ford F-150 XLT SuperCrew, and I was hoping to get larger all-terrain tires. I was planning on either getting the NITTO Terra Grappler G2s or the Boyfriend Goodrich KO2s. I currently have a leveling kit on my truck, so that should give me a bit more clearance on going up a few tire sizes. I was told by some F-150 company workers and they said that the biggest size would be 285/60-18. Is this true? Also, could I get away with going up to 285/65-18's or would that cause rubbing?

Lastly, which of the two brands of tires would you recommend for overall quality?

Thanks in advance!

Added (1). I came across suggestions of getting 35x12.5-18 tire. Would this size tire work, or would that rub? If it were to rub, how much trimming would need to be done for it to fit properly?

The factory usually puts the widest tire that will safely go on the rim on the truck. Check-out. 1010Tires.com. They have a tire/wheel calculator that will give you all the facts.