When your wheels are at full turn, how much room do you have at the front? Also do you know the backspacing of your new rims? If they're pretty close to stock, then a 265/75/16 would put you right around where you are at now. I'm using this size because they're are alot more tires available in this size. Check to see how much space you have in their to increase it and your next size up would be a 285/75/16. On your 88 it might be a tight fit with no lift. If you don't mind cutting a little of the inner fenderwell out it will give you another inch or so for the width of the tires.