Air supply on road, pretrip for short runs?

Constantly reinflating a tire is going to weaken the sidewalls. Not so much the reinflation, but the sitting/driving underinflated. Eventually the tire is going to fail. If you're lucky, all it does is shred itself. If you're unlucky it's going to take out the mudflap/bracket. If you're REALLY unlucky, it's going to damage the frame rails.

The nightmare scenario is the tire blows while a car is next to it, damaging the car/causing the car to crash. At that point you'll be faced with a Billboard Lawyer that's going to try and bleed you dry.

A new tire is cheap compared to a lawsuit.

 

How many miles have you moved it at 90 psi? How long has it sat still at 40 psi? Both conditions will weaken the tire. If you continue to use a tire with a known leak, it will blow - you just don't know when. Most companies will require any tire below 70 psi to be replaced because they've learned this lesson. It's cheaper to change a "good tire" at the shop than it is to blow one on the road.

Find the leak and repair it, or replace the tire.

 

If you’re counting your nickels and dimes, purchase a tire plug kit Amazon or eBay. Btw, the rubber grommets on the stem dry out after a while. See if can tighten it up a bit. Better yet, find the slow leak first. And take it from there.

 

Look up sidewall “zipper failure”. An all steel tire sitting low and stressing the sidewall can cause the steel plies to fold, pinch, and break. Do not lean over or stand in front of that tire while airing. Just 20 psi can rupture it. That is why clip on air chucks and inflation cages are used.

 

Here you go

 

I know you are trying to justify your actions which is alright to do but sometimes professional advice should be over what you think is right. We all have seen some nasty things with tires, and yes one tire being low can cause problems for other tires and be a hazard on the road.