It really depends on how big the spacers are. For instance if you put 1 inch spacers on the optional black ORP wheel, you end up with the same offset as a PRO wheel. So no added stress to anything since the offset is the same as a PRO.
Just make sure you torque everything correctly and you'll...
No mods needed. These tires are wider than stock, but the circumference is the same, so no difference. And if you get a flat, you can use the OEM spare. We got hammered with snow here in NE Ohio and the Wildpeak AT4W are great in the snow. Really pleased with them.
I went 285/65/18 with the Falkens. They're SL rated, same diameter as the OEM 265/70/18 tires on my ORP, so I had to only buy 4 tires instead of 5, since I can use the spare if need be.