Well your kinda stuck , cause you can only get lower pro tires if you have a bigger diameter tire!!
your 16" calls for a 55 series tire, its computed to have that diameter , and you speedo will be altered if you go lower pro on that 16"
trust me, i had 16" mille miglia mm11-2s on my tour with a 40 series tire, and when my speedo said i was doing 65 i was really doing 59!! 6mph difference. So it may keep you from getting a ticket and help you on the lower end of a race, but that is the only plusses.
it will kill you on top speed and overall engine performance!
sorry, but you are stuck my friend.
