I went from 225 to 245 on my G30 without changing any gears .... still takes off like a jack rabbit N now I get better MPG. My white van has 4.10 gears from the factory. Id be more worried about tire rub when going bigger.
My red 4X has a 3" lift to fit 315/75/16 12" wide with 4.56 gears ft N rr. It came to me with 275/75/16 tires I changed no gears on that one either.
You might want to try running the new tires then order gear paks.
And both vans still have way more motor than tire ....