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So I've seen most people talking about their cars' max sidewall being 40-45... but I checked the HCH-I, and it, of all cars, has a max sidewall of 30 psi. When I went in to get my tires rotated, my dad and I couldn't believe it wasn't even 35 (and of course my dad wouldn't hear a word of getting it around 40 psi...).

What's up with this low ceiling? Does anybody know why it's so low? Can I afford to push it to 38-40?

So I've seen most people talking about their cars' max sidewall being 40-45... but I checked the HCH-I, and it, of all cars, has a max sidewall of 30 psi. When I went in to get my tires rotated, my dad and I couldn't believe it wasn't even 35 (and of course my dad wouldn't hear a word of getting it around 40 psi...).

What's up with this low ceiling? Does anybody know why it's so low? Can I afford to push it to 38-40?

This doesn't sound right. This doesn't meet any tire standard I am aware of.

So let's get details. Size, make, and model tire please.

Also, it would be helpful if you took a photo of the sidewall that shows the pressure, so we can see for ourselves.

Wow, that's a little hard to believe. It is possible that a previous owner bought some cheapo tires that have lower sidewall pressures.
We bought a 97 Civic DX for Heather last year , and I was surprised to see Cooper tires with 35 PSI on the sidewall.
By the way , you have some very nice numbers for the HCH. Most teenage drivers only know how to mash the gas all the way to the floor and then hit the brakes as hard as they can.

It sounds more like the pressure on the door plate, and not the pressure on the tire.

You have to read the tire manufacturing max. cold setting printed in fine print on the side of the tire. Lower cost tires are normally 40psi some 44psi and better tires 51psi. H

By the way , you have some very nice numbers for the HCH. Most teenage drivers only know how to mash the gas all the way to the floor and then hit the brakes as hard as they can.
What can I say? I'm learning from some of the best here. :D

Also, everyone else, I guess I was stupidly mistaken (for some reason) that the max pressure listed on the door was "max sidewall"... Yeah, not sure where that logic clicked in my head, haha. My dad got me pretty good tires (low rolling resistance and the like), though I don't remember exactly what they are. I don't know why the people would check the door for the max tire pressure instead of the tires themselves, but I realize now how fairly ignorant they must be (and I am, by extension) for using the door max, not the actual tire max.

My apologies to the general lot of you, haha, I didn't consider that the standards for the stock tires (or whatever it is the max door pressure is based off of) don't apply to all other tires.

I was worried about filling up past 35-ish PSI because of winter, but since it hasn't snowed here in Blacksburg (at least while I've been here), I guess I might go ahead and bump it up to 40 some time. Any other suggestions on this, while we're (read: while I force it) on the subject?

"door max"The pressure stated on the door placard is the automaker's recommended pressure. It is NOT a "maximum" in any sense.

I'm tending to split the difference, between placard in the door and the 40~42 psi range a lot of hypermilers recommend. Basically, I try 40~42 for a tank or two, then drop to 36~38 range (assuming placard is saying something around 32), and see what it does to the mileage. In my experience with a Prius with the low profile 17" tires, the drop to 36~38 made little or no difference to the mileage, and did ease the harsh ride somewhat.

I wonder too if long term use of extreme pressures is detrimental to suspension components?

I made the mistake of casually mentioning this to my dad, saying the 30 psi is just what the manufacturer recommends, etc., and of course he got into a whole rant about how that's to keep me safe, how higher psi means stiffer tires and a rougher ride and how things will fall apart in the car because of that.

I'm always torn between what I read on these forums and the cautious advice my dad gives me. He used to drive a Prius (and got quite excellent gas mileage, even without a lot of hypermiling techniques that aren't common things like DWB and DWL) and was part of a Prius forum, so I know he's not necessarily ignorant to a lot of these things, but I guess my judgment's just clouded by these glory stories I read on here of you guys having up to 45 psi in your tires without real problems and having the complete opposite told to me by my dad, who is by no means a bad or ignorant driver.

Higher pressure does definitely add to NVH (noise, vibration, and harshness). NVH definitely makes life harder on suspension components and "rattlers," OTHER THINGS BEING EQUAL. Thing is, other things are not equal. The placard pressure of the car maker assumes we are all agressive drivers. Hypermilers compensate for higher psi with their greater attention to the road and slower speeds (just as wanna-be cowboys compensate for something by adding metal balls to the unused hitch receivers).

As you pay more of the costs and gain experience, you can implement your own judgments in such things. On his dime, his judgments should certainly hold sway.

Popular(?) article written by a cop about tire pressure: http://www.cleanmpg.com/forums/showthread.php?t=11652

FWIW, I typically drive with 50PSI (yes, that's actually over) in my tires, have just shy of 100k on the clock, and haven't had a problem.

You could push it a little because that's 30 psi "cold". When the tires are warm, the pressure will be higher. It just depends on your definition of "cold" and "warm". ;)

I ran a set of tires at 35 vs the car's sticker calling for 32. They wore down on the shoulders, a clear indicator of underinflation. As an exercise, walk through a parking lot some time and look at the tread wear on tires. Most are inflated at or below the carmakers' specification, and the results are predictable - bald shoulders but some remaining tread in the middle.

The automaker's pressure is a compromise of noise, ride comfort, treadlife, traction, fuel economy and other factors. If we adjust the order of those to prioritize fuel economy over the others, higher pressure is the answer.

After saying all that, don't push too hard against Dad. It's not worth straining that relationship for something this minor.

Higher pressure does definitely add to NVH (noise, vibration, and harshness). NVH definitely makes life harder on suspension components and "rattlers," OTHER THINGS BEING EQUAL. Thing is, other things are not equal. The placard pressure of the car maker assumes we are all agressive drivers. Hypermilers compensate for higher psi with their greater attention to the road and slower speeds (just as wanna-be cowboys compensate for something by adding metal balls to the unused hitch receivers).

As you pay more of the costs and gain experience, you can implement your own judgments in such things. On his dime, his judgments should certainly hold sway.Yeah, alright, that all makes sense... And yeah, it is technically his car, so...

Popular(?) article written by a cop about tire pressure: http://www.cleanmpg.com/forums/showthread.php?t=11652

FWIW, I typically drive with 50PSI (yes, that's actually over) in my tires, have just shy of 100k on the clock, and haven't had a problem.I want your car. :( (I've gotten into a mode of convincing myself that getting an HCH-II would make my entire life better. It doesn't help that my HCH-I is also the powder blue model, and I constantly get **** from my friends about it, haha.)

You could push it a little because that's 30 psi "cold". When the tires are warm, the pressure will be higher. It just depends on your definition of "cold" and "warm". ;)

I ran a set of tires at 35 vs the car's sticker calling for 32. They wore down on the shoulders, a clear indicator of underinflation. As an exercise, walk through a parking lot some time and look at the tread wear on tires. Most are inflated at or below the carmakers' specification, and the results are predictable - bald shoulders but some remaining tread in the middle.

The automaker's pressure is a compromise of noise, ride comfort, treadlife, traction, fuel economy and other factors. If we adjust the order of those to prioritize fuel economy over the others, higher pressure is the answer.

After saying all that, don't push too hard against Dad. It's not worth straining that relationship for something this minor.Just to clarify, I'm running 35 (we argued with the guy for a bit before he said fine, he'd do 35 instead of 30), so it's not exactly that bad.

My dad did say he'd really, really prefer it (which clearly isn't a matter of preference) if I left it at 35 psi, and I'll respect him and do just that. The moment I have the money, though, I might go for a mid-'90s Civic that I can aeromod slightly and do this with... :'D

I want your car. :( (I've gotten into a mode of convincing myself that getting an HCH-II would make my entire life better. It doesn't help that my HCH-I is also the powder blue model, and I constantly get **** from my friends about it, haha.)
I know the feeling... my first car was a rusted out station wagon. Don't worry, life does get better.

The moment I have the money, though, I might go for a mid-'90s Civic that I can aeromod slightly and do this with... :'D
Please, don't rice it.

Mid-90's civic? :D

Please, don't rice it.
Nooooo, not rice, haha. I mean like rear wheel skirts, a Kammback mod, etc.