Precisely! It's sort of a loophole

Trust me, the tires can take a lot more than the max sidewall claims. Tire manufacturers don't want to get sued for tires exploding or whatnot, so they set the "max" way lower than it can actually handle.


The tires are in this pic are from a Crown Vic. Max psi rated at 44. These are inflated to 100psi.

From Driving Under Pressure: Editorial & Features at Officer.com as linked earlier in this thread.

 

I run about 30-32 PSI cold. For all four tires.

 

Check out this thread:
https://www.fitfreak.net/forums/gene...tire-wear.html

The guy says (FYI - This is with no rotation or alignments done) After many replies with links to tire wear charts, he says
I personally don't think the placard is adequate psi and I dare to set mine [way] higher, but I honestly haven't tested it over any duration. So, prove me wrong!

I would be interested to know, those of you who have always kept them at 32, how have your tires have worn? Even? More on the outside? When have you had to have them replaced (and is this with or without rotation)?

 

Bear in mind that was with no tire rotation and what did I say about bumping up the front tire pressures up 3-4 psi over the recommended door sticker? Front engine FWD = front heavy car.

But 50 psi is way overdoing it... if you play with your tire pressures, you'll definitely notice a difference in they way a car drives with just 3 psi of air difference in the tires. And if the alignment got knocked out of whack (hitting a curb or bad pothole) then your tires would most certainly wear out unevenly.

I've done 50k miles on RE950s on my RSX in the past using about +3/+1 from the door sticker without any issues. There was enough tread left on them at that point to go further but wet grip is something I like and it was starting to hydroplane a bit at times.

 

Please note the pressure on the tire sidewall is the MAXIMUM cold tire pressure recommended by the tire maker. He knows when you exceed that pressure you will not like the ride, the titre life, and perhaps the cornering.
Cold is the tire pressure before being driven more than a couple of gentle miles.

The door jamb pressure is the recommended tire pressure by manufacturers for most comfortable ride.

The usual tire pressures around 35 psi are better for performance and mpg.

 

Actually, inflating my RSX-S to 35 or 36 psi would cause it to loss grip earlier in the dry twisty roads. The bulbous effect most likely reduced tire contact patch with the road. So keeping psi to within a moderate level above recommended is as I've said before, best and safest for general street driving.

 

I don't understand how some people are running in the 50 PSI range. My Bridgestone say that the max PSI is 44 PSI. Lol!

 

A few PSI up or down will not make a drastic difference. I do agree that depending on what you are doing with the car and the condition they are driven in that the pressures can be tweaked. In general the best for mileage, wear, ride comfort and designed handling the tire placard is best. The absolute best way to judge what tire pressure is best for the car is to get ahold of a tire pyrometer and check the tire temps across the tread in 3 places after going for a decent length drive. The idea is to get the temps as close across all 3 spots as possible. If the temps are hotter on the outside edges vs the center then more pressure is needed, if the center is hotter then the pressure is too high.

The ballooning effect is there despite the steel belting. The tire is in theory safe to the pressure stamped on the tire at the load also stamped on the tire, the problem comes when the tire doesn't have that max load on it and only the load of the vehicle (which shouldn't be as high as what the tire is rated for).

On my race car I fine tune tire pressures based on temp and handling every run...sometimes I am adjusting as little as 0.5psi and it can make a difference.

The other item to understand in regards to tire pressure ratings on the placard is safety...the manufacture also designs the vehicle to be out of control if it happens in a certain way...to ensure maximum safety in the event that a driver looses control they want the car to loose control in a straight line so that if an impact occurs the maximum effect from the airbag will be utilized. Thi means designing in natural understeer in the vehicle so the front tires loose grip before the rear, this will result int he vehicle not spinning (in theory) and hitting an object with the front of the vehicle. For maximum performane different pressures would be used vs the placard, for better mileage you can go higher but handling and wear may be an issue.

 

I just inflate my tires until they burst, then back off a little....

 

I guess that's one way to find what the real max pressure is....when you back off a little do you use a gauge or just go by feel?

 

LOL - both of those methods are equally effective.. heehee

But, back on topic. Mine are set to 34 psi all around, ride is decent and we'll see about tire wear. 1600 miles so far.

 

Never went that high with the RSX - I think it was 33.5 up front. Since the Fit Sport starts at 33 on the door sticker, I added 3 to try out 36 front.

 

Max cold, independent of car.

 

Sorry, but I'm embarrassed that my tax dollars are employing this idiot. What he is saying is probably going to get the city sued. He is absolutely wrong.

This is another thread where this subject is being beaten to death. I will attempt to put this to rest.

* The pressure on the sidewall has nothing to do with the pressures that the manufacturer recommends or that you should run. They are just maximums that you should not exceed. Read any tire warranty booklet or your owner's manual, and they will tell you the same.

* These Honda Fits use a stupid, mandated TPMS system, and Honda cheaped-out on the implementation supporting only 4 sensors and all 4 sensors are thus calibrated for the same pressure.

* The Fit has a clear front weight bias, yet uses the same pressures (and tires) all around (see above as they are forced to do this). As a result, the front tires are proportionally overloaded, and the rear are underloaded. This also has the purely intended consequence from Honda of giving a cushy ride and sub-optimal handling that is safer for the masses.

* To produce the most even tire temperatures across the surface of the tread under street conditions, I have determined the best tire pressures for my Fit Sport are 38F and 28R cold. This, coincidentally, slots 5psi above and below Honda's recommendations considering Honda wants you to rotate your tires. Running 38F and 28R greatly improves the contact patch/load distribution across the tread both front and rear optimizing the traction and tire wear. Unfortunately, 28 psi is bumping right up against the limit for the TMPS to kick in which is 80% of 33 psi or 26.4.

This is what I have found as I do with every car I own. Of course, you can run whatever you want -- even 100 psi, just please don't drive near me.

 

Tire pressure debates piss me off. So i'm gonna keep it simple. I go by Honda's recommendations on the door jamb sticker. PERIOD.

As for the handling guys I read a sweet article in Car and Driver about testing tire PSI for grip.

To sum the article up, take some chalk and rub it on the outermost part of the sidewall and a little on the outside tread block. In an empty parking lot get up to a fairly good speed (25-30 mph) and corner in a complete circle several times (like a mini skid pad). Check where the chalk has disappeared. If some is missing from the tire wall, your PSI is too low. If there's still some on the tread block, your PSI is too high. Add or Remove air and repeat until your desired results are achieved.

^^Never tried this method in person, but it sounded like a damn good idea

 

Me, too! Unless you have a good understanding of the physics/implications of not running the stock tires pressures, run what Honda tells you!

This is an OK tuning technique if the only thing you have is a piece of chalk. The problem is that chalk won't diagnose alignment problems such as camber or other limitations such as body roll and tire flex/construction differences. I'm a firm believer in that the tires' treads will tell you a lot about how it is performing (temperatures, tire wear patterns, feathering, etc.)

 

Curious how you determined those pressures. Did you use a pyrometer and check for even temperatures across the tire surface/contact patch - single driver only during the drive?

 

Ah! Finally, an intelligent question. This is single driver, ordinary street driving, and with an infrared gauge. A pyrometer would probably be more accurate, but for street driving, I think the temperature is pretty well stabilized and matches well with overall tire wear patterns (on other cars/Fit is too new). For track use, you would likely want something different, but I think is in the ballpark since it intuitively follows the general weight distribution of the car without being too anal and triggering TPMS. In sum, it's probably not a half-bad place to start, but those "who know" will want to further tweak/fine-tune.

 

Forgot to ask - you have Bridgestones or Dunlops? Either way, it makes me want to try out more pressure combos... 33 seems a bit high in the back... but the choice as a compromise since the 4 sensors all can be tuned to only 1 pressure level. Currently at 36/33 and I think I might try out 36/31 next.

 

You're ABSOLUTELY right. Tread wear is a MAJOR indicator of alignment angles. I'm glad someone understands that.

As for the "tuning method", i didn't say it was fool proof.
I think it'd be good for the DIY guys that aren't hardcore racers.

nonetheless, + rep for knowing some shit