265/35-19 ,,,,275/35-19,,,,285/35-19 all have a slightly higher rim to grown and give a slightly softer ride and if i remember the speedO is only off 3 to 400 rpm the 285 is 26.9 tall just don't go over 27" without centering the rear wheels, and u will need adjustable rear suspension on all the rear links.
you can keep the front and the rear factory rims.