Tire Size Question

[Discolater]

I saw the threads on here about lifting the Nitro and the “body mods” needed to clear larger tires in the front wheel well.
I also saw I would be able to run 30.5 X 10.5 X17 tires, after modification.

My question is what size is the LARGEST tire I can run. I see on the adds for Daystar lifts they advise a 245 x 70 x 17.
If I used a different offset wheel, could I go with a 265 X 70 X 17? Or what about after the Body mods, could I run the 265’s or even wider?

And last but not least, how do I compare tire sizes? I see sizes such as 245 X 70 X17, and then I see them measured in inches like : 30 X 10 X 17. How can I convert between the two?

Thanks in advance for any help,

Ethan