[NJAkkord]

FYI, I keep my 2018 Touring tires at 45 PSI. I'm one of those who ignore the recommendation and use the 90% rule of max PSI. My tire manufacturer max is 50 PSI, thus I inflate mine to 50x0.90=45.

This rule has worked well for me during the many years of car ownership. Your dealer may be applying the same rule for tire pressure. However, you might want to ask them their reasoning for using 45 PSI.

33 PSI for a 50 PSI max tire means your tires are only inflated to 66% capacity. Personally, this seems unusually low and more likely underinflated. But, then again, that's Honda's recommendation. So, choose what you're comfortable with.

As far as the TPMS goes, did you drive the required speed and cumulative time after selecting TPMS Calibration? Here's what the manual says (see the bold):

TPMS Calibration
• TPMS cannot be calibrated if a compact spare tire is
installed.
• The calibration process requires approximately 30
minutes of cumulative driving at speeds between
30-60 mph (48-97 km/h).
• During this period, if the power mode is set to ON
and the vehicle is not moved within 45 seconds,
you may notice the low tire pressure/TPMS
indicator comes on briefly. This is normal and
indicates that the calibration process is not yet
complete.

If that works for you, then by all means continue inflating to 45psi. I'm surprised that over the years you have not worn out tires in the middle tread faster than on the side blocks as overinflation (which 45 is) rounds out your tires. While your specific tires can handle 45psi and even a max of 50, they are not designed to run at that pressure for maximum wear, comfort, fuel economy, and safety. Inflating them to 45 or 50 makes the center tread bulge thus making you run on less than an ideal tread patch. Traction diminishes, stopping distances increase. Honda recommends 33 psi for maximum patch contact, longest wear, and maximum comfort. I generally tend toward 33 knowing that the heat of the day AND rolling heat will increase that by a few pounds on its own. Like I said, your tire pressure is up to you, but beware of the pitfalls of going significantly above recommendations.

 

[NJAkkord]

Car manufacturer "recommendations" are just that. They're also usually softer than other markets because they feel Americans want a softer ride. As long as you're not going above the max PSI of the tire, you're not over inflating it to have the center bulge like you're stating. Going over the car manufacturers recommendation and the tire makers max PSI is two different things entirely.

They may be softer, but not because of pressure. Honda chooses the size of the tire, the suspension set up, the recommended pressures, and the speed and load ranges specifically for the car, not to make it soft for Americans but to balance comfort, efficiency, handling, and safety. Sorry, over inflation occurs long before reaching the tire manufacturer's maximum. It's pure physics since the tire's bead is stationary and cannot change. Extra pressure is exerted on those parts that can change and that's the sidewalls primarily and tread secondarily. I live on a dirt road. The easy way for me to tell if I'm overinflated is to see how the dirt is deposited on my tread. Too high, say 40+ and I have the center tread dusty and the blocks relatively clean. It's an interesting sight. Run your tires however you want, it's your car, and I'll do the same for mine. The OP on this internal thread must be beat up running 45+psi on 40 series 19 inch tires. OUCH for sure. Oh, and don't forget... your tires gain approx 2% pressure for each 10 degree rise. Tires can easily rise 50 degrees just by running them at higher speeds for a relatively short period of time. That's 10% pressure increase and even more if they were last measured in colder climates. Have we exceeded the sidewall max yet?

 

[NJAkkord]

Tire manufacturers aren't using untested ratings. They use physics and extremes when determining max PSI. Sidewalls and increase pressure from heat build up are factored in (amongst other considerations). So, even if you set your tires at max PSI, it won't exceed the sidewall limits and tread limits.

Also, the manufacturer's max is not the physical max of tire pressure. The stated max is well below the physical max.

While i agree with you and the ability to run a tire at the manufacturer's max, what is missing is how that tire, the wheel, the pressure, the suspension, and the rest of the setup works together as a unit. Honda didn't pick out of a hat some arbitrary tire size, pressure, and even suspension settings when they designed our cars. They designed all of these factors to work together. Ever wonder why a reputable tire shop won't sell you a tire ouside your car's size, load and speed ratings? Because they don't want to be sued if something happens. I agree with you that I could easily pump my tires up to 50 psi and run them safely, well, relatively safely. That contact patch, which you are ignoring, gets both narrower and more importantly shorter when pumped toward the max. That is the ONLY thing between your car, it's ability to steer and stop and perhaps your life. Like I said before, it's your car, your tires, your life. Believe me or not that 45 is way outside what Honda expected in the tires on our cars. Will it drive? Heck yeah. Will you have problems? Maybe, maybe not. Did you diminish the safety system Honda designed, oh yeah. And not to mention your teeth... those low profile tires pumped to the max and potholes galore have to loosen some teeth (just kidding pal). Let's just agree to disagree. Run whatever pressures you are comfortable with and I'll do the same. Most of my driving is high speed interstate and I'll run mine at 35, yep above the recommended. For me that's a great balance between comfort, handling, economy, and tire wear.

 

[NJAkkord]

Your making tons of assumptions based on visual cues and some parts of science. You have no idea about the other parts and how the tire is manufactured, it's stress point is ect. Tires are made with, and the max PSI is based on, all the things you just mentioned and more. You really think a tire manufacturer doesn't know all those issues when posting the max psi? Your tire on a dirt road can be heating unevenly or simply contacting differently and have nothing to do with overinflation. Your leaning heavily into science and physics yet ignoring half of them with your comments. Your physical obeservane of what you precieve as having more dust in the middle is completely irrelevant and proves nothing. There are so many other factors involved. Now if you said I kept the tires there for 10k miles, and saw more wear in the middle tread than side tread that's a different story. Some of this also has to do with the compound/ the tire. Continental tends to run softer tire and then edges round easier so I compensate with a couple more psi.
And yes it's because of pressure american rides are softer for some makers. It's a trick Porsche among other have used for years. Some manufacturers have different sizes and pressures for different markets. It also sometimes recommended to run a size smaller for snow.
Bottom line is as long as your staying within the tires max psi, your fine.

Like I said before, your last sentence about sums it up. I never said you shouldn't, I simply offered reasons why the manufacturer of the car vice tire recommends a certain pressure.