1) I have Nissan Sunny 2006, The car come with tires 175/70 R14, could we replace with 185/70 R14, without any affect
You will have some effect but nothing serious. I'd think you wouldn't have any tire rubbing, but your speedo will be fast by 1-2mph. If you do use that size make sure you replace all 4 at the same size. Why not stick with 175 size, not available?