My current setup is 35x12.5r18 with the wheel size being 18x8.5 with +25mm offset and everything is perfect but as I have seen some people on here where their tire rubs the spindle when trying to mount or flex so I'm worried about this new setup...

New setup, same tire size with wheel size being 18x9.5 with +25mm offset (V-tec off road 326)

So my question is, how will I be able to run such a wide wheel and tire with having a +25mm offset / 6" backspacing?

 

The people having issues with rubbing have been mounting 35x12.50 tires on the OEM 20x8.5 inch wheels which have 6.5 inches of backspacing. It's a combination of the 8.5 inches width and the deep 6.5 inches of BS that causes some 35x12.50's with aggressive sidewall designs to touch the knuckle/spindle where the upper ball joint is located.