[booreux]

What is the recommended tire pressure for the Limited with 18" rims? Picked up my car the other day and the TPMS in the dash says that 3 of the 4 are 43 and the rear right is 39. Seems kind of high to me.

 

[Pappa60]

Look at the driver side door sill. It will give you the recommended inflation. I believe it is 36 psi.

When I picked up mine they were over inflated too.

 

[Fastskiguy]

I'm going 45psi on my 17" LX rims FWIW. They were 41 from the dealer....and they say 51psi cold max on the sidewall so I'm pumpin' 'em up!

 

[irpilot]

Look at the driver side door sill. It will give you the recommended inflation. I believe it is 36 psi.

When I picked up mine they were over inflated too.

What is the recommended tire pressure for the Limited with 18" rims? Picked up my car the other day and the TPMS in the dash says that 3 of the 4 are 43 and the rear right is 39. Seems kind of high to me.

I would definitely look at the driver door sill as Pappa60 suggested. Proper tire pressure is very important and tires should not be over or under inflated. The numbers that are listed on the door sill will be for cold pressures.

 

[kentfield1951]

51 PSI is way too high. Set it to 36 -38 PSI at the most. My car had about 10 PSI too much air in the tires when I drove it off the dealer lot, and got home and lowered it with a good air pressure gauge.

 

[Blitz]

51 PSI is way too high. Set it to 36 -38 PSI at the most. My car had about 10 PSI too much air in the tires when I drove it off the dealer lot, and got home and lowered it with a good air pressure gauge.

+1. Pacifica tire preasure should be set at the recommended preasure of 36 psi. Having too high tie preasure is dangerous just as too low is dangerous, and 51 psi is way too high. That is the max preasure for the tire, not the recommended preasure for the vehicle/tire combination.

 

[dolee7]

tire pressure

I try to keep 36 lbs in them but living in Wisconsin its awfully hard to do so in the spring and fall.The temp fluctuates so much at them times its nearly impossible to do so. Right now today mine were on 34 at 70 degrees but tonight it might get down in the 40s so they will be much lower.I usually wait fo a 40 degree day and put them on 36 or 37 then they will stay above 32 most of the winter when its colder out.It will drive me crazy keeping up with it so I half gave up on it. I use to check them once a week but dont now as I got burned out on it. Besides I kind of like the ride a little with slightly lower air pressure.

 

[kryptik-pacifica]

I'm going 45psi on my 17" LX rims FWIW. They were 41 from the dealer....and they say 51psi cold max on the sidewall so I'm pumpin' 'em up!

This is quite dangerous given as tires warm up, PSI naturally increases. You're really giving your tires only a 6PSI buffer to expand. Overinflation can easily lead to blow outs, but what it will always do is create uneven wear across the tire tread causing the center of the tire to wear faster than the sides given the center will bulge out a bit more than the side. In doing this, it also means less tread is making contact with the asphalt thereby reducing traction and grip. In dry weather you may not feel too much of a difference; however, in wet weather it'll be a completely different ball game since the tread pattern that diverts water out and away is no longer able to do so since it's not actually touching the ground to continue to divert the water. See the attached link for images that show the difference in water diversion for proper vs overly inflated tires.

Since it won't let me post links yet, google Winter Tech Information - Air Pressure vs. Wet Performance and there should be an informative Tirerack link.

Ultimately, the max pressure stated on the tire is merely what it's rated for and almost never the maximum of what is appropriate and safe for your vehicle. Because different cars and rims have different PSI requirements, tire companies can't merely match what the avg wheel and car is because it would never accommodate a car that may need a couple PSIs higher. So they rate it and stamp it's peak to accommodate any and all possible cars and wheels. The manufacturer will always have the optimal PSI posted on at the door based on the car's size, weight, car type, curb weight, wheel base, etc.

With all that said, high speed plus hot tires, plus increased PSI means a far greater chance of blowout (or in wet conditions hydroplaning) potentially leading to a life threatening situation for you, your passengers and the cars around you.

 

[Fastskiguy]

I've heard this on other threads and heard arguments supporting higher tire pressure too with the only drawback begin a harsher ride. Yesterday we did 130 highway miles and started at 44 psi, ended at 46.5 psi. It's hard to know what to believe but if it's dangerous to run 45psi then why would a manufacturer put 51 psi max on the sidewall?

I should add that my driving style may not stress the tires much (see below)

 

[irpilot]

I've heard this on other threads and heard arguments supporting higher tire pressure too with the only drawback begin a harsher ride. Yesterday we did 130 highway miles and started at 44 psi, ended at 46.5 psi. It's hard to know what to believe but if it's dangerous to run 45psi then why would a manufacturer put 51 psi max on the sidewall?

I should add that my driving style may not stress the tires much (see below)

You were given plenty of great explanations in this thread. If you want to go against the manufacturers recommendations then all the power to you. This horse has officially been beaten dead.

 

[kryptik-pacifica]

I've heard this on other threads and heard arguments supporting higher tire pressure too with the only drawback begin a harsher ride. Yesterday we did 130 highway miles and started at 44 psi, ended at 46.5 psi. It's hard to know what to believe but if it's dangerous to run 45psi then why would a manufacturer put 51 psi max on the sidewall?

I should add that my driving style may not stress the tires much (see below)

Fastskiguy:

I don't disagree with irpilot; however, I'm going to respond just one more time to try and help you understand to save your life, your passengers lives, and the lives of fellow drivers around you, but this is the last attempt. I do apologize to others for the length of this write-up, but I hope you read it through carefully (multiple times if necessary).

In response to your 2.5 PSI increase, unless your on the south side of the hemisphere experiencing summer season, right now we're reaching colder weather temperatures. So, the ambient cold air will keep the tires cooler such that they don't expand as much and/or as fast as in the heated weather (in the heat you'll likely experience roughly around a 5-6 PSI increase if not more). Also, elevation/altitude can affect tire pressure as well (air is thinner, etc.). With that said, that does NOT mean you can safely drive with higher PSIs in cooler weather. What it means is what you're seeing in the low PSI increase is POTENTIALLY reasonable in the current temperature. I bet if you were in roughly 90F+ degrees, your tires could easily hit close to 50 if not exceed 50. That's how much it can potentially expand both in the heat and at consistent high speeds.

Now, in terms of the tire's "Max" PSI, you have to remember that this is the tire manufacture's spec not the car manufacture's. The tire company did NOT engineer/design/develop/build your Pacifica. Chrysler engineers did. Now, if you want to make the argument that you should be able to run higher PSI on your tires that exceed standard manufacturer recommended PSI, it means you're hauling a ton of cargo such that the increased weight within the vehicle offsets the added pressure thereby pressing down on the tires enough so that the entire width of the tread contacts the pavement. If you're not hauling a large load, then overinflating does everything bad that I've mentioned before and will try to rephrase below to see if it helps you understand better. Now, it doesn't mean that if you're not hauling anything that you should underinflate your tires. The manufacturer's recommended PSI accommodates single passengers plus additional passengers. With that said, you should view the tire manufacturer's max PSI as part of maximum load in which the vehicle can haul. There are calculators online you can search for that'll calculate vehicle cargo load weight to additional suggested tire PSI. In fact, usually the car's driver side b-pillar or the manual will state what PSI to set the tires based on load which can easily be referred to as well.

As for the "only drawback being harsher ride", this is only part of it. As I said, if the sides of your tire treads are off the pavement and the center is on, only the center wears which creates uneven wear. This is just common sense. Next, with less rubber contacting the road, you're essentially crippling your handling and traction ability. It's why race cars use fatter tires for better grip, greater tire to pavement contact, etc. They're not running skinny tires for a reason.

Lastly, if you go to Chrysler's site > Owners > Owners and service manual > Tire Info Supplement. You can say they're printing these warnings to avoid lawsuits. Honestly that's partially true. The other 1/2 is simply because they don't want you killed in their vehicle because that's 1 less person to continue buying their vehicle in the future. So, unless you're a automobile/tire engineer, you should really consider trusting the manufacturer who hires engineers to design a car that will not kill you if operated properly as designed. And, if you don't trust them and what they "suggest" is proper operation, you should not own their car or any car for that matter because all car manufacturers do the same with suggesting a proper PSI which at the moment you continue to disagree with and disregard. And finally, if you really want to still own a car and want to disregard the manufacturers, there's a ton of research to be found on google with answers from tire experts such as Tirerack.

From the official Pacifica manual -
"Warning:
Overloading of your tires is dangerous. Overloading
can cause tire failure, affect vehicle handling, and
increase your stopping distance. Use tires of the
recommended load capacity for your vehicle. Never
overload them.

Warning:
• Improperly inflated tires are dangerous and can
cause collisions.
• Underinflation increases tire flexing and can result
in overheating and tire failure.
• Overinflation reduces a tire’s ability to cushion
shock. Objects on the road and chuckholes can
cause damage that result in tire failure.
• Overinflated or underinflated tires can affect vehicle
handling and can fail suddenly, resulting in
loss of vehicle control.
• Unequal tire pressures can cause steering problems.
You could lose control of your vehicle.

 

[Fastskiguy]

Hey Kryptik, thank you for the detailed writeup and I did read thru it twice I'm not trying to be a troll here, I'm just coming from ecomodder.com and some of their arguments make sense.

A lot of the comments are about killing people with my 44 psi tires. I couldn't find much info on how a vehicle handles with "higher than placard" pressure but this study by the nhtsa shows *shorter* braking distance as we go from 17 to 35 psi. This article was about the dangers of low tire pressure so no data above 35psi...but still, you'd expect shorter distances at 25 than 35 but according to this they are longer.

TIRE PRESSURE SURVEY AND TEST RESULTS

see chart III-7 and III-8

Then there is this one...showing an increased coefficient of friction at 35 psi over 28 and 20 psi, it's a big chart at the bottom. There are some braking charts in there too.

FEA chapter III. tire pressure survey and test results

If you don't feel like clicking...here's one conclusion

"These data indicate that stopping distance is longer with lower psi for every case except for two cases with the full depth tread with ABS on the Dodge Caravan.� Full depth tread tires had shorter stopping distance than � depth tread tires on wet surfaces, but not dry surfaces, and vehicles with ABS had shorter stopping distances than those vehicles without ABS.�"

Anyway....I'd appreciate your thoughts

 

[PacificaLimited]

Why is this even a debate...? Not trying to be negative, but why would you NOT just set your tire pressure to manufacturers' specifications and get-on with your day... as opposed to arbitrarily choosing to exceed it... and LOOK FOR validation online to support that decision...? You can FIND arguments and reasons on ANY topic online to support your thoughts. If there is even the SLIGHTEST chance that deviating from spec' could cause harm or damage, why bother risking it?

I am not chastising you... do what you want... I am really just perplexed why anyone would choose to dispute and ignore manufacturers' claims like this. (shrug)

 

[BrettP]

So far the only folks over inflating my tires is Chrysler, haha! Three of them were ~49psi when I drove off the lot. I keep them at ~36-38 psi now.


If you are in a loss of control vehicle accident that involves lawyers, insurance companies and lots of money your tire inflation levels can (and will) be used as evidence against you when they are significantly off the door spec. My experience here is as a juror on such a case, not as a tire expert.

 

[kryptik-pacifica]

Fastskiguy,

Out of respect, I clicked the link to view some of the information. First off, if you look at it, it doesn't show the results of overinflated tire. In fact, it shows under-inflated tires up to average typical properly inflated tires of 35PSI. The entire study seems to discuss under inflation. Where's the results for overinflation? Nowhere in this survery. In fact, as I've shown before, both major under-inflation and over-inflation impacts traction, drive ability, etc. major under-inflation also misuses the tread on the tire, causes the tire to flex more than intended, etc. which ALL can affect things such as braking. In the Tirerack article I asked you to google "A tire that is slightly under-inflated will apply less pressure to the center of the tread and it will become slightly concave... A tire that is significantly under-inflated will allow the center of the tread to collapse and become very concave, trapping water rather than flowing it through the tread design." Meaning, you're now using more of the sides of the tire when the center is needed to start the diversion of water. The sides on it's own doesn't divert water well as it doesn't have a starting point. Water dispersion starts from the center then outwards depending on the tread patter. Since I'm assuming you're using all season tires, usually water dispersion begins at center and shifts outwards. It's what the pattern is designed to do. So, what it tends to do is with water trapped under center, it's lifting the car above water thereby reducing braking distance. Again, common sense.

Now with using the assumptions you've created for yourself which is based on this survey more PSI is better regardless of manufacturer recommendation and even tire manufacturer recommendation (they always default to recommended you consult your manual for proper PSI for your exact vehicle spec), here's my response to this illogical assumption placed on a meaningless survey to the conversation. If you feel the increased stopping power of a fraction of a foot means more to you than proper tread wear which means less need to buy new tires as frequency thereby polluting the world with more tire rubber, less stability and traction which impacts your ability to maneuver around objects and turns (especially turning on a dime), and less contact in wet conditions potentially creating a situation of hydroplaning which essentially renders your improved braking distance null since you can't brake to stop when you're hydroplaning, then so be it. Also, they're only speaking of 1 brand of tires for braking. Are you running Goodyears or another brand, because every brand is different in their rubber compound, tire sidewall technology, tread patterning, etc. Not all tires are created equal. It's why Snow tires work better in snow and not dry pavement. It's why Summer performance tires don't function well in snow if at all. Could they have tested Goodyears that just happen to brake better when overinflated? Sure. Does it mean ALL tires overinflated will brake better? This answer is inconclusive based on the report you provided. So, essentially the test result is crippled and not even a proper sampling to make as strong of a definitive determination as yourself. I used to run business intelligence for a big data type company. One of my specialties was to make data tell a story. Any story. Any story the company needed and any story the client wanted. Picking 1 brand of tire and possibly only 1 tire within the brand does not make for a good test sample. Cars and ABS systems are not created equal as well. And chances are they tested vehicles with just 1 passenger and no additional weight, cargo, etc. So, they're not testing for live situations. They're testing for the sake of testing in a controlled test environment. What part of driving out there with others a controlled test environment for you?

Everything in life is risk reward. Most people won't risk the increased negative risk to the minimal positive gain with over inflation of tires as you're experiencing with feedback from others. You seem to be the exception to that rule which I'm not stating as a compliment. I'm always reminded you can't reason with the unreasonable and you can't apply logic to an unreasonable situation.

In closing, it's funny you mention you're not trolling, yet it really still feel like you are if you continue to try and come up with evidence to prove your reasoning after all the proper evidence provided that disproves your reasoning. There will be no evidence that proves what you're doing to your Pacifica tires to be safe and proper. If you start to tell me that race cars will typically increase PSI, you're not a race car, you're not driving 100+MPH, etc. I used to track race and at over 100MPH the tires do something totally different than standard street driving with your minivan. So, please don't even think about going there.

*DROP THE MIC

 

[Fastskiguy]

Why is this even a debate...? Not trying to be negative, but why would you NOT just set your tire pressure to manufacturers' specifications and get-on with your day

It's really about rolling resistance and gas mileage but I think the tires might last longer too and subjectively it seems a little more sporty in the turns. The suspension...however...might wear faster. And I'm not opposed to a comfy ride But I really get a kick out of eeking out the mileage and the van seems to roll really well with its current setup.

One thing I'd like to try is to see if there is a difference between 45 and 35 psi with regards to gas mileage.....should be easy, just need a bit of time.

Thanks for the reply though....I'm not sure now what I want to do...

 

[kryptik-pacifica]

Fastskiguy: Major Injury and possible death to your family should have been sufficient to persuade you to begin with. If you don't have a family then major injury and possible death of others should be reason 2. Reason 3 is major injury and death to yourself (unless you're suicidal to begin with then please don't take others with you as I don't ever understand the point of murder suicides). Those are your 3 most compelling reasons. It isn't that hard.

Moderator: I'm not sure if this forum works like other forums I participate on, but if so please lock this thread so that there can be no further replies. The topic is beyond answered and contain sufficient factual information to help other members with questions regarding tire PSI. Thank you.

 

[Fastskiguy]

So far the only folks over inflating my tires is Chrysler, haha! Three of them were ~49psi when I drove off the lot. I keep them at ~36-38 psi now.


If you are in a loss of control vehicle accident that involves lawyers, insurance companies and lots of money your tire inflation levels can (and will) be used as evidence against you when they are significantly off the door spec. My experience here is as a juror on such a case, not as a tire expert.

Well litigation risk, now that's something else I believe in...because it doesn't have to be based on facts!

But how does this tire pressure thing work with the different trims? With my factory installed Toyo's on 17" wheels the number on the door is 36psi. Do all of the wheel/tire combo's have the same 36psi sticker on the door? Because you'd think that Michelins on 20" wheels would be a little different. Or maybe not?

And then you have replacement tires and aftermarket wheels...which seems like a big can of worms. What was the result of that lawsuit you were a juror in anyway??

 

[dolee7]

tire pressure

would think they would not grip as good on wet pavement or snow with to much pressure in them.Besides the ride would be to firm for me.If itf 90 out my 36 lb. tires turn into 40 or 41 lb tires.When all said and done put in whatever you want its your van.

 

[BrettP]

Well litigation risk, now that's something else I believe in...because it doesn't have to be based on facts!

... What was the result of that lawsuit you were a juror in anyway??

I agree with you Fastskiguy...it doesn't have to be based on facts or even right vs wrong especially in a civil case. Our case was based on plenty of "black box" data (incorrect tire pressure was just part of the cherry picked data chosen to make the accident victim look like he negligently caused the accident) but very few actual facts ... the black box data was used to weave a plausible story that was mostly "emotional spin" IMO performed so well by a lawyer that a member of the jury (yes, a juror!) cried and the insurance company panicked and settled a case they could have won. We were sent home after 3 days of testimony just as we were supposed to start deliberating.