According to this:http://www.1010tires.com/TireSizeCalculator.asp

I've been running 245/35/20 up front and the diameter difference from stock is 3.37%. Which means I was in risk for brake failure according to that website. Anybody else running tire sizes that's too difference from stock? My rears are fine at 275/30/20. I'll be switching to 19s soon and I was hoping to get beefier tires but that's no longer the case.

 

That is just recommended. You don't NEED to run factory specs. A lot of people run a 245/35/20 in the front.