Although this maybe one of the single most important settings (that we have control) I don't see much on tire pressure and tire pressure values..
Few things come to mind, first there are only a few tire pressure gauge manufactures that produce an accurate reading, PCL comes to mind.
I have a digital from Autozone (typical) and is 3 LBS off of a master gauge. So, my gauge reads 30 LBS, a master gauge reads 33 LBS. This
range is typical with 90 % of tire pressure gauges. Now, this brings me to the TPMS found (at least) on my GS350. The TPMS is very close
in accuracy to a master gauge, maybe a pound plus or minus.. I was surprised by this a I thought that the TPMS in most cars were best guess.
Anyway, in many days of testing with hot tires (driven 1.5 miles or more) and cold tires (set overnight), I found that 33.4 on the TPMS (cold), or 30.5
on my digital is the sweet spot (hot tires, as much as 36 LBS). Toyota recommends 33 PSI, which as it appears is close to where I am.
I have been obsessed (as a few of my buddies have stated) about tire pressure and checking them regularly. Too high pressure cause premature tire wear,
premature suspension wear and interior rattles and squeaks. I can always tell a vehicle has been maintained correctly by how quiet the interior is and that comes from in part maintaining proper tire pressure through many years. Most car owners I see at stations are filling their tires up when they are hot or have been on the road for a while. Maybe its time we re-educate
drivers on the proper process of checking tire pressures? I'll start with my girlfriend and work down to my sons, they don't have a clue either!