It's more about a minimum of weight or pressure that affects it. So the higher the pressure the more likely it is to flex the road where a small vehicle with light pressure might not make it flex at all. The heavier it is the more the weight will flex the subsurface and cause more damage.

https://www.forbes.com/sites/lauriewinkless/2023/08/30/how-roads-fail-and-why-theyre-set-to-get-worse/

"To give you an example of that impact, let’s do a quick calculation. Here in New Zealand, the heaviest vehicle allowed on (some of) our roads is the 50MAX truck. It has nine axles and a total weight of 50 tonnes, so the load-per-axle is 5.55 tonnes. The best-selling car in NZ in 2022 was the Mitsubishi Outlander. It weighs 1.76 tonnes, so its load-per axle is 0.88 tonnes. The fourth-power law says that to calculate the relative stress that these two vehicles apply to a road, you take the ratio of their loads-per-axle and raise the result to the fourth power. In this case, (5.55 / 0.88)4 = 1582. In practical terms, it means that a 50MAX truck applies as much stress to a road as 1,582 cars (or quite literally billions of bicycles)"