The sign posted by the National Park Service invited off-road vehicles to the beach. I didn't read the fine print. It advised off-road drivers to reduce the air pressure in their tires to 21 pounds per square inch. Low-inflation tires have better contact with shifting surfaces, such as sand and snow.

I didn't do much thinking, either. The tires on the 2006 Range Rover Sport Supercharged weren't ordinary four-wheel-drive rubber. They were 20-inch-diameter Continental SportContacts; and they were designed for double duty, with a decided bias toward high-speed running and crisp handling on paved surfaces.

Such tires generally are not good in sand or snow. They commonly are referred to as "low-profile," or "low-aspect ratio" tires. The aspect ratio is the relationship between the height and width of a tire expressed as a percentage of a tire's width. Just think of it this way: Narrower-width tires with tall sidewalls tend to do better in sand and snow than wider-width tires with short sidewalls. But wider-width tires with low sidewalls usually are better for running fast on dry, paved roads.

I had the wrong tires and wrong attitude in the wrong place. I was huffy. The 2006 Range Rover Sport is available as the 390-horsepower Sport Supercharged, or as 300-horsepower Sport HSE. It is an exceptionally competent machine on and off the road. But its correct use assumes you have common sense enough to follow instructions. I didn't. I was smitten by technology.

For example, the Sport Supercharged and Sport HSE come with the trademarked Land Rover Terrain Response system, which electronically adjusts the vehicle's stability, traction control and related systems to improve travel over specific surfaces -- paved roads, grass, sand and snow, and substantially more demanding off-road courses. I blithely selected the sand-and-snow option and started on my way. Dumb.

I did not deflate my tires, as recommended by officials of the National Park Service, who know a thing or two about going off-road. I ignored the aspect ratio of my tires, and all that meant. I assumed that the dense, wet-packed sand leading to beach would remain that way forever -- which simply means that I need to figure out a way to get to the beach more often.

The packed sand became shifting, loose sand, and I got stuck. It was embarrassing, sitting there in a fancy Range Rover digging tire holes in the sand. But I collected myself, settled down, and recalled all of the things I had learned -- but had earlier failed to apply -- in Land Rover off-road driving schools. (Land Rover, by the way, is the division of Ford Motor Co. that produces Range Rover vehicles.)

I chose not to deflate the tires, figuring that further reduction of their sidewall height in that circumstance would only make matters worse. I selected the four-wheel-drive-low gear and began backing out of my self-made dunes very slowly. I continued in that mode until the tires touched the hard-packed sand again. I was chagrined, but relieved -- upset that my thoughtless bravado had gotten me into trouble but happy that the competence of Land Rover's engineering and some good instruction in its schools had gotten me out without the need to call some Outer Banks mechanic in a Chevrolet tow truck to pull me from my misery.

Lesson learned: I never again will assume that when the National Park Service officials are giving off-road driving instructions, they are talking to people who aren't sitting in the luxury of a Range Rover Sport Supercharged, or some other fancy, high-performance four-wheel-drive vehicle. Many of those people in Chevrolets, Fords and Jeeps passed me as I was spinning my wheels. They were running on proper tires, deflated in the manner recommended by the park service.

Sand is sand, and Mother Nature has a way of beating you upside the ego. I got a good whipping; and it was well deserved.