I run my Latitude Tours at 40psi. Any higher and braking would be excessively affected and the tires would wear first in the center of the tread. In addition hard tires make the ride harsh and jittery.

Weight in the car and weight of the tire/rim combination do hurt mileage. However those effects are minimized with hybrids. And it's pretty easy to explain why.

Yes, it takes more gas to get more weight moving or heavier tires rotating. But you also recoup most of that additional energy when you brake. More weight means more energy to convert into battery charge, as does de-rotating heavier tires. However, as there is some efficiency lost in the conversions, not all the additional energy will be recovered. So additional cargo or heavier tires are not a big deal for a hybrid.

Whereas on a non-hybrid, braking that extra weight or de-rotating those heavier tires is completely wasted energy.