The modern metric equivalent to tire size A78-13 is going to be a 175/80-13. You won't be able to use any of the tires we carry though because they are for trailer use only.
There is a difference between the way trailer tires are manufactured versus passenger vehicle tires. Trailer tires are built with a thicker sidewall to handle more vertical load. Passenger tires are built for cornering more with lateral forces in mind. view full answer...