Hydroplaning is most likely to occur when driving on wet roads with tires that have

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Hydroplaning happens when a layer of water builds up between the tire and the road, so the tire loses direct contact and traction. The tread on tires acts like a water-scooping system, channeling water out from under the tire. When tread depth is inadequate, there isn’t enough void space to evacuate water quickly, so a slick film forms and the tire can’t grip the road.

That’s why insufficient tread depth is the best answer here: it directly undermines the tire’s ability to clear water and maintain contact. Very deep tread would improve water evacuation, reducing hydroplaning risk. New tires have solid tread and evacuate water well, so they’re also less prone to hydroplaning. Inflation pressure affects the size of the contact patch, and extreme over- or under-inflation can influence grip, but it’s not the primary factor in hydroplaning compared to worn tread.