Tire size and tire inflation pressure determine tire load capacity, so larger tires with higher inflation pressures provide more load capacity than smaller tires and with lower tire pressures.
Properly inflated tires distribute the load evenly across tire footprint and stabilize its structure. On the other hand, underinflated tires not only have a negative impact on tire wear, durability and rolling resistance, but also significantly reduce tire response and precision to the driver's input.
To check the effect that tire inflation has on performance on dry roads, drivers were asked to ride the same car on properly inflated tires and tire with 30% underinflation. Why 30% underinflated? Because it is the level that most tire pressure monitoring systems will show low tire pressure warning. Test was run to check tire performance at its limit. As expected, properly inflated tires showed excellent responsiveness and predictable handling. Buy underinflated tires were slower to respond to steering input to initiate maneuvering, with front tires feeling out of sync with rear tires during transitions. Overall underinflated tires felt uncooperative when changing directions on dry roads.
In other words, underinflated tires took away the built-in performance capabilities of a tire. So if you want to enjoy everything your tires have to offer, keep them properly inflated!