They are 235/60x15 all around. I have a pair of the 255s but I looked at the date codes and they are from 1997.
Never run a tire older than 7 years regardless of the amount of tread remaining, or things like this can happen:
These tires were 10 years old and had around 100 miles on them.
To check a tire date code go to the DOT imprinted number on the side. If it is newer than the year 2000, it will say the year code as the last number:
For example: BHVENX71 3 7 04 = week 37 of 2004
If your tire was produced before 1999, it will say something like BEVENX71 3 9 8 = week 39 of 1998.