If you run over a nail with either type, you'll probably get a flat, from penetration of the tread. So yes, on paved roads the P metric will probably be as flat resistant as an LT. But on the pavement, your sidewalls are up in the air, away from sharp objects
. Off road, and on the wrong gravel roads, it can be a different story, and your sidewalls need to be tough enough to resist getting cut.
When I was a real farmer, I hauled a lot of square bales with a pickup. Had P-metrics on an old 1/2 ton F100. I'd ruin tires by getting stubble puncturing the sidewalls. But I had a good supply of used tires from my "town pickup" so kept on using them. The other farm pickup had 16s, couldn't use the 15" P-metrics, so had LTs. No flats in the stubble fields.
About 4 years ago in the little town I live in, we got lots of snow and little plowing except for the main routes. Then we got 3 days of high 30s/low 40s weather, just enough to soften the snow to slush, and it froze again. The ruts were about 5"-6" deep on the side streets. Two friends with P-metrics ruined tires with cut sidewalls the first week of that. Another friend with a compact car left their exhaust system behind on a really deep rut
. I ran the pickup with LTs exclusively during that time, and had no trouble at all. The tire shops were doing good business that winter.
So my vote is for LTs. In my experience they are a tougher tire.
