I'm going out on a limb on this but I'm willing to suggest that this is the result of a combination of factors. It doesn't look like a case of overloading, the trailer doesn't seem to be that big. Older truck, overheating and hot temperatures this past weekend. I'd guess maintenance was the root cause. The radiator is older, maybe a little plugged, possibly not filled to the top nor adequate anti-freeze. Older radiator cap might let the radiator boil over prematurely. Maybe an old hose blew?

Just guesses, but to me it is a reminder of how important routine maintenance is to proper performance. Towing puts a big load on the truck and all the more reason to maintain it right.

Like I said, I'm out on a limb. For all I know a vehicle ahead of it kicked up a stone and poked a hole in the radiator.

Red

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2005 Titan KC SE, Helwig, True-Track, ARE MX Canopy