When we were doing "Parts and Service until Midnight" at work, one evening an elderly lady pulled into the service drive with her then-late-model Cavalier 2dr. The complaint was that she had requested a service station attendant (for the ONLY full service gas station in town, at the time) to "check her tires". The attendant looked on the tire sidewall and inflated the tires to that pressure, which was 45psi, as I recall. When done, the car rode much harder with more bump impacts being felt.
Our service advisor drove the car around the lot, took it back and put the tires back down to what they should have been.
Initially, I suspected that she had been riding around with a friend in the friend's Lexus, then felt that her Chevy should ride the same, but was never designed to do this. When the service advisor came back, told her what the issue was, and that he had corrected it, at no charge, she was pleased.
I am not concerned about weight carrying capacity, as I know that issue was addressed by the OEM when they designed the car. I'm not really concerned with better steering response or effort as the chassis designs take care of that. What does concern me is how much time can be spent in "coast-down" from highway speeds or on local streets (at lower speeds), aided by vehicle aerodynamics, too. To me, extended coast-down relates to better vehicle performance and (by watching the "Instant MPG" readout on the Driver Info Ctr) ultimate fuel economy. Through decreases in the torque required for the wheel to turn against the road surface. You might be surprised at just how much mpg can increase with a few changes to driver behavior! NOT doing the hyper-miler orientation, but learning to coast (more so than not) up to a STOP sign rather than "driving" up to it and then stopping. In such activities, which send the mpg readouts up to 99mph, rather than 20mpg or so, plus using moderate acceleration to get to cruising speed (rather than the gradual acceleration that allegedly worked with carburetors, in earlier times). Plus using the cruise control (on the highway, for many reasons) can result in fuel savings.
Due to how the particular tire sizes and rim widths interact, those slightly-elevated inflation pressures do NOT result in center-rib tread wear. The last set of Defenders on the Impala went for 100k miles in my driving. They were replaced due to other issues than tread wear, although they were getting thin enough that wet weather performance could start to be compromised.
We each have different orientations about tire inflation pressures and related vehicle impacts. I know the OEMs built their tire pressure recommendations on many other things than just weight-carrying orientations, plus the desired handling characteristics desired for "general population safety" and tire durability. I know that the standardized pressure for all four wheels might be easy to orchestrate, but can still result in one end of the vehicle having less of a capacity margin than the other end, so I devised my proportional approach to such, so each tire has similar reserves, but at slightly different inflation pressures. That approach led to increased tread life, better handling response, and a firmer ride, for me. And tire treads that "wore flat" on both ends of the car. To me, getting those benefits for just a few psi difference was beneficial for myself and the tires. When I was formulating my orientation, I used a multitude of data from trusted magazines I had in my collection, owner's manuals, and some industry publications. PLUS my trusty K + E slide rule. Considering EACH factor in the process. To me, I was successful and the '66 Newport I prototyped it on liked it too.
Whatever works for you and keeps your spouse happy, your judgment call.
CBODY67
