Just from experience.. with a Mustang I have found the ratio didn't matter. You have so many other things going against you that you won't even be concerned about that
Some would argue this, but of the vehicles I have driven in the winter, my Mustang is probably the WORST pig in snow and ice, and up here that is plentiful mixed with minus 40 degree celcius days.
For the money I would have spent on winterizing, snow tires and second rims, I bought an old chevy and bomb around in that all winter. Cheaper in the long run especially if you happen to come across that little old lady in her cordoba that has no clue what a brake pedal is.