As iaa has correctly stated the 195/60 is the closest to the original 175/65 in terms of diameter. Remember that the aspect ratio is quoted as a percentage of the tread width so the wider you go the larger 5% of that width is going to be. On a narrower tyre like a 155 then going up to a 175 would probably require two steps down in aspect ratio.
I think you are splitting hairs when you talk about upsetting the balance of the car due to differing radii, the difference is only 3.25mm, (175mm x 0.65=113.75 vs 195mm x 0.6=117mm) bearing in mind that the tread depth on a new tyre is around 7mm and the legal limit is 1.6mm giving a range of 5.4mm. You only really need to worry about different diameters on the same axle i.e. left and right as opposed to front and back. Remember a lot of high performance rear-wheel drive cars have different sized tyres on the front and back.