Used truck tires are good, they will wear like iron.
If the OP didn't know how to tell age, read the DOT code on the tire. One side will have the date code at the very end. The first two numbers are the week of the year (01-52) the next numbers are the year (2010=10,2013=13 etc)
You wont find LT's in that size.
I know how to convert tire sizes just was working on trailer at time and yes I can read for I work for a tractor trailer company and do 10-12 tires a day because we won't run over 3 years old. Finding 16s with my lug patter and offset is being a pain in the ass and most of my pulling is up and down around mountains occasional interstate