Tire size up

Those tires will be slightly taller and that is it. I doubt you will notice any difference.

With the 65's your 65mph speed is 65mph. Going to a 70 will result in your speedometer at 65mph when you're actually doing 67.22mph. You can simply search tire size speedometer calculator and see. At that size difference you will not notice it unless you're getting over 50mph. My old Jeep I had went from reading 60mph doing almost 75mph when I went to the 33inch tires I had on it. However it was a dirt machine and almost never saw pavement. Just be weary that with that size change your speedometer will be off a little. You'll doubtfully notice any power loss as the change really isn't drastic. When you go a lot bigger you'll notice the larger the tire; the less power you'll feel on the butt dyno.

Did you do a lift on the truck at all? Would it rub?