Upsizing tires on factory rims

I've got the factory 235/70/16 Goodyears on aluminum rims on my Escape still, and they're getting a little slippery in the rain and I've started looking at new tires. I'm considering keeping the stock rims and putting a slighty wider tire on there. I remember hearing the rim can handle a 255 width but I'm not sure what the sidewall would be? 60? I'd like to stay near the factory overall height. If anyone knows thanks!