Be careful, low air pressure in a tire will cause the tire to heat
up, that heat will cause a separation between the tread and side
walls. When the tire comes apart at speed bad things can happen.

This is a problem sometimes with replacement tires vs the door
sticker, the vehicle manufacture wanted one thing and the tire
manufacture know what the tire is designed for. If you put a tire on
that calls for a max of 60 psi and you are running it at 40 psi it
has 30% less pressure than it should, that adds up to heat.

Rob
becida@comcast.net