My cars have always ridden smoother with over-factory psi, but Id get premature tire wear. Sticking to factory specs on this one.

 

I think the dealers overinflate the tires so they don't get flat spots sitting on the lot.

 

Flat spots? Not with the newer tires today. I can recall the belt-ply tires of my 61 Vette getting fat spots sitting in the garage for a couple of weeks. I've never experienced flat spots tough on my Mustang or F150 truck when they both sat for weeks when I was on business trips.

 

I'm still "investigating". Definitely only happens at over 100km/h, more like 120 (~75mph), on the same road, reasonably quiet and very acceptable up to then.

My car never sat on the lot, very very few V6s do around here, it used to be almost impossible to find one that's not an auto/vert, they only last a few days. I found that 40psi makes these tires (least on this car) very skittish in the rain, moreso as the temps fell. Much better at 35psi though I do kind of prefer the "hardness" feel of 40. Except for the high-speed whine the tires seem OK for OEM, I've had plenty worse...

 

32psi cold just like the door post decal says is the best tire pressure for proper handling...

 

^ I gotta try 32 still. I've never liked it though, including in any of my other Fords that specified it. Put 32 with the IMO very soft stock suspension and I dunno...could be like driving a bowl of Jello.

Edit: oh yeah, in case you missed it at the beginning, some dealers are delivering these cars/tires with 40psi cold (and not just to me) for whatever reason, IOW no accident.

 

The OEM Pirellis on my car were the worst for "flat spotting" of any car I have ever had. Routinely happened in the winter with only a few days of idle time. The second set of new take-off Pirellis were also the noisiest tires I had ever had. Much happier with Kumhos installed last summer.