We just bought a 2001 Lund Mr. Pike a couple weeks ago. We went on
vacation last week, and of course had to take the boat with us. About
40 miles from home, the driver's side trailer tire blew out while on
the freeway going almost 70mph. Then, about 100 miles later, the OTHER
trailer tire blew out - this time we were only going 60mph, as we were
paranoid after the first blow-out.

These were 14" tires that, yes, were original, so were 6 years old.
They looked good, though. No obvious wear or cracking. I ended up
having to get 15" tires from TSC as they didn't carry 14" ones. Being
that it was 6:00 on a Saturday in a small town, there wasn't really
any choice - either get the 15" tires or get nothing at that point.
The guy at TSC said the 15's are better tires anyway, and would fit,
which they did. He also told me that this happens quite often, and a
lot of people get new trailer tires ~every 4 years, whether they look
like they need replacing or not, as many times trailer tires will go
without any warning, like they did with us. He also told me that 14"
tires are not commonly carried. Another guy that this happened to had
14's and he had to get 15's to put on the trailer, which he changed
out in the TSC parking lot. So if all these boat trailer have 14"
tires, why don't retailers commonly carry them??