Proper tire pressure

The Show
41

Skip,

As someone who writes manuals for tires, I can tell you that there is new stuff in the manuals that wasn’t there a few years ago. You should read the manual just to know what new things may have been learned.

Remember the Ford / Firestone debacle you’ve referred to? Do you think that nothing was learned? I know of 3 things that have changed as a result. Some of those things are listed in the manuals currently being published.

Please, please, read the manuals. It won’t hurt anything and you just never know - you just might find something you hadn’t thought about!

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Ok, ok, just to satisfy you all, I went and got my manual and actually looked at both the tires and door sticker.

The difficulty with 3/4 ton trucks is they come from the factory with several tire options. Some have D rated tires, some have E rated, and depending on the ordering dealer, brands may change as well.

I have Michelin LTX’s on mine E rated. The tire indicates that the maximum load on the tire at 80 PSI is 3150 pounds each. My truck weighs about 6500 lbs, maybe a shade more empty. Approximately 70% of it is on the front axle and 30% on the rear when it’s empty.

On my rears, I have 65 PSI. And 70 PSI in the front. Bear in mind with that 3500 lb straight 6 Cummins engine in the front, the curb weight is extremely heavy.

Referring to the manual.

Page 74 says: Safety Checks you should make outside the vehicle, under tires it says check for treadwear, nails, screws and stones in the tread. BTW, I did flip out a couple gravels when I checked the air. It also says check wheel nuts for looseness, well, they are underneath the hub decoration doo hickey, and I’ve taken lug nuts off these trucks before with their close threads, They ain’t coming loose, and BTW, there was no rust there, so likely that’s ok. I’m not getting a torque wrench out everytime I leave the house.

BTW: There’s 496 pages of the manual plus the 65 page engine addendum, a Lemon Law bill of rights book (Kentucky’s runs out at 1 year or 12,000 whichever is less, lawyer explained that to me on the F250 junker I bought in 04, I don’t think I’ll read that book seeing as how I have about 35,000 miles on it now.

Skipping to page 304:

Big warning label: Caution, overloading your tires is dangerous: Duh

Another Warning Label: Improperly inflated tires can cause dangerous situation: Note: It has several bullets in it, one of which suggests that all 4 tires should be equally inflated, that’s not what the door sticker indicates, so I’m confused.

It appears they copied information from a small car manual into the truck manual. They go into a rant about cold pressure of truck being in garage, in driveway, air temp etc trying to worry about 4 pounds on way or the other. Door sticker does give a loaded and empty weight.

Warns that I should not drive loaded over 75 mph for extended periods of time. Truck tops out at about 95 mph due to gearing, really with $4 a gallon diesel, I’ve not been running 70 here lately to conserve fuel, I did pull a boat out of Florida once with it at about 85 mph. However, max capacity on this truck is around 20,000 lbs, Boat weighed around 3500+6500 truck equals about 10,000 GVW or half max, so I guess I was ok.

2 pages of stuff on Donut spare tire. They don’t put these on 3/4 ton trucks, again, more useless information. The lugs are so tight on these trucks that likely the included lug wrench isn’t strong enough to remove them, so If I do have a flat on the road, I’m going to call a wrecker to come get it or someone that has portable air and a tire to change onto it.

2 pages of stuff on how to identify a tire that’s worn out. 4 pages on how to use snow chains. I’m in Kentucky, before I’d get done reading it, the snow would be melted. The truck is 4wd, so really it’s not necessary. If I can’t negotiate the road in 4wd, I have no business being on it. Rotation pattern for tires. End of that section, next page is how to shut down runaway engine. I’ve seen that happen to a big truck, he threw a 1x board up against the air intake and it made one heck of a mess.

Oh, there was a couple pages on buying replacement tires. It said to buy tires exactly like the ones on it. How does the book know what’s on it? I’m sure the D rated tire trucks have the same book, and what about the guys that got Firestones instead of Michelins on theirs? These are the same exact trucks, there are options for tire and wheel combos on these vehicles based on your use and purpose. Cutrate dealers will order trucks with Generals or some other cheaper tire to cut price. Michellin is top of the line as is BF Goodrich in the D rated tires.

Page 475 gives the codes used on tires to indicate tread wear.

BTW: I’m within 5 pounds of what’s supposed to be in the front according to the sticker, and my rears are in between the loaded and empty range. Since modern gas station pumps generally have a limiter on them to 35 pounds, I keep mine ready for what I expect to do.

Now fully educated.

Skip

43

Skip,

This post is not to pick on you, but is supposed to be for those who have followed the thread this far and may be in a quandry about what the manual said compared to the actual practice - and why so many people said to read the manual.

It is obvious that the vehicle placard called for Load Range E tires - max pressure 80 psi. That means putting Load Range C tires on the front was not what was advised - and, as was found out, didn’t work.

But there is another issue here. Either the Load Range C tires were inflated more than the maximum indicated on the sidewall - and that increased the risk of an impact related tire failure - or the load carrying capacity of the tire was reduced - and that increased the risk of a load related tire failure. Neither of those situations is good. (This assumes that the placard size was used, but in a LR C)

At any rate, the lesson here ought to be that there is stuff in the manual that might avoid problems - which is why it is there.

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" THe label on the door was made for the tires of the particular tire manufacturer under contract at the time of printing of the door sticker. Ultimately, go with the inflation on the tire because this is what the present manufacturer recommends for your tires."

That makes no sense. First using that logic, would suggest that every car must have the same needs, without regard to weight distribution, suspension etc. The tyre manufacturer has no idea what car those tyres are going on.

It also is in direct opposition to the tyre manufacturers themselves:

References:

http://www.tiresafety.com/

This is sponsored by a tyre manufacturer Bridgstone - Firestone and instructs the reader to check the owner’s manual for the correct tyre pressure.

Here is another from the Goodyear site.

Check Your Air Pressure
Keep your tires properly inflated and you could improve gas mileage by more than $1.50 every time you fill your tank. The recommended tire pressure for your vehicle is located on a sticker inside your driver-side door or noted in your owner’s manual.

You might also try the US Department of transportation.

http://www.nhtsa.gov/cars/problems/E...intenances.htm

They say:

You can find the correct tire pressure for your tow vehicle in the owner?s manual or on the tire information placard.

So if you look at three authorities, the Tyre manufacturers, the car manufacturers and the US government they all agree. Why do you disagree?

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First of all, those Range tires were on another truck, not this one. I’ve long since sold that truck. I did run it with those tires on it for 4 or 5 years though. It became my backup vehicle and the one I used quite a bit helping to work the elk population in Kentucky. That truck ran up and down haul roads on strip jobs chasing helicopters at 70 and 75 miles per hour, and didn’t have problems, it just didn’t handle as good as I’d have liked.

For what it’s worth, the max psi of those tires was 50 lbs. I ran real close to that in them and no, the sky didn’t fall. I drove that truck around for 4 or 5 years like that and had no problems. It’s just one of those things for reference that I’d not want to do again. BTW: That truck was an F250 diesel, Navistar’s 7.3 diesel is a little lighter than Dodge’s Cummins, not by much, but it is lighter.

Also, for what it’s worth, that damned prize manual is nothing more than a listing of lawyerized warning labels 99% of which fall into the Duh category IMO. If you’ve not got sense enough to know that an over loaded truck is dangerous, or it’s possible you could run over something in the road and bust a tire, or you should make sure you have the right amount of air in your tires or else, Maybe you ought to be riding public transportation. There’s a heck of a lot of junk in that manual that looks to be standard such as the 6 or so pages on the little spare that don’t apply to trucks.

All you needed to know was on the plackard and tire, nothing in the manual worth opening IMO.

For what it’s worth, I’ve seen those trucks with C and D range tires on them from the factory. People use trucks like that for everything from hauling to pulling to going to get coffee in the morning. What would be better for me might not for someone else. An older guy might not appreciate the thrashing tires with 70 lbs of air in them will give you and might be perfectly satisfied with his truck having a softer ride but less capacity. The same thing goes for these cars. Look around, there’s cars driving around on 20" wheels with a half inch tall tire that looks like a solid tire on an old John Deere. Do you suppose the manual would be much help with that? People do all kinds of things over time, they change tire sizes, change wheel and tire sizes, change brands, types.

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In reply to you Norm,I have to completely agree with you here.
My days, at the dealership years back, we had a chance to take a (complete tire course).This was not mandatory, it was if you wanted to update your skills!,so I said why not. This being said, you are very right about what you say about tire manufactures here. And this was back in 2006/7 that we had this course, right from the head guy down at continental tire, came to the dealership, and our course began.
Now, the very part that caught my ears the most was the tire pressure, he began to say these exact words.
(his words) we must make positively sure, that the tire pressure on the sidewall is what you place the tire pressure at, no matter what!! wow, this being said I had said to him, Iam in a habit of (never) putting in 32 lbs, I have a thing where I was using 35p.s.i. (as a standard) growing up (dads words) son,you have to make sure your tires especially in the winter, are set to 32p.s.i. iam very sure most heard this also?. this being said, I was totally wrong he came back with ouch thats not good!!!.
his words were very explicit, in his terms that if it said 38p.s.i. on the sidewall, then it’s a must that 38 p.s.i. is followed, and he went on to explain in terms, that this is the main reason of blow outs and underinflation/over inflation when we do not keep the man specs, we can not only void warranty, and will strictly apply. So in saying this, after this guy left, our principle at the time (principle meaning the owner of the dealership many might not know this term, but it is the owner of the dealership,anyway he used this policy to get things done, and was set in his ways, when vehicles arrived, the service writer was to firstly, do the normal walk around report on findings etc etc, but were also required, to do a tire pressure check (had to be done especially on newer vehicles). this might seem kind of rough, but it was a dealer policy, after this rep left our dealership.So if the sidewall had 50p.s.i. max, it had to be set at 50 p.s.i. . To this very day, I keep these things I learned top of my list, and actually I have, had better wear from my tires, you name it.Only the one time, did i ever have a flat with new tires, and the first thing that was checked was the remaining 3 tires for their pressure, and it was at the sidewall specs, and I asked the tech (i knew this but was curious) why, are you checking the pressure on the 3 other tires (his answer) I just want to make sure the 3 others are at 50 p.s.i. or in the area, and he did say that if they weren’t he was instructed to let the service manager know, !!! I said thats great i’m not the only one who took this course, after all (smiles) he never did take the same exact course, but his service manager had said to always make sure they were in the area of the sidewall. So hope this helps, if I can find the business card, it would be interesting to get a rep from the company to come on here, and he will reaffirm what iam saying here, I keep everything lol. I finally got rid of old hydro bills from 2000 lol… just me, but i did keep his card, thats a fact. where it is now??? good one, but i will see if i can find i,t but for a fact it was continental tire they were a dealership tire and still are In places in canada, to this very day. Thanks and hope this helps somebody out.

~Dave tech 30+Years and still here and there, these days. but not full time anymore.but it’s like riding a bike, you dont forget things. these days if you have a computer in hand your king lol…

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“Beefy Norm” hasn’t posted on this site for… probably… about 10 years, so the chance of him seeing your reply is… slim.

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Your long hard to read post needs to be sent back into cyber space . That way someone will not see that nonsense and put their tires at the maximum pressure on the tire side wall instead of what the door plaque has as the correct pressure.

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Good Morning Carolyn , @cdaquila . I know you don’t like to close or remove old threads but this one has a lot of bad information ( if goofball ideas can be called information ) .

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Hi Dave:
Welcome to the community.

Yes this may be an old thread, but the way the dates are displayed, many of us find ourselves replying to old threads.

Unfortunately, as you noted, the PSI number on the tire sidewall is still used by some. I’ve seen one case result in a blowout. I’m sure there are many more.

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+1
I didn’t even bother to read that “wall of text” until you pointed out that it contains dangerous misinformation. Yikes!

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Doesn’t everyone come here with information that is based on their experiences?

And isn’t that information frequently correct, sometimes incorrect, and sometimes having content that brings disagreement?

And isn’t the value of a forum like this to discuss information that we may not agree with? If we simply shut down comments because we think they’re wrong (for whatever reason), then why even have a discussion?

And then the question becomes whose comments should be shut down? I don’t recall any certification criteria needed to establish ones comments being more important or trustworthy than others.

Leave the comments open. If we disagree, then let’s discuss where we differ so we can learn from each other.

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excuse me but i dont appreciate being called a goofball
in reply to you what do you know about tires? please do tell! because yes this could mean (life or death) and i have never been the death business nor never will be. I have many years of safety awards (to which comes first in my work).
this said I did send off a email to continental tire just a few minutes ago to confirm what i said here leave it here and we will see when i get a reply then you have all the rights to call me if iam wrong to which iam not.
people that use these types of words know much i guess thanks for your words anyway… typical when someone knows?? well you know

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Any claim that the sidewall pressure is the correct pressure is wrong, it’s that simple.

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just received this, but trust me when I say this when I start something that has to do with motor vehicles I complete it to the very end in my time I have seen so called techs forget to even tighten up/torque nuts to specs and wheels fall off vehicles, you name it i speak from experience. not on google there was no google in my day (sorry) dont believe everything you read on any search provider. take my word i would not (ever) risk or (yikes) somebody’s life} with what I say In fact I have said things, that have actually saved lives in my career, and dealership certificates for my efforts. and sorry if you dont like my grammar/ not the right ,…! or whatever they are but we cant all be the same the good lord made us all different

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Subject re: tire pressures

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  • Date Created: 02/11/2021 10:15 AM
  • Date Last Updated: 02/11/2021 10:15 AM
  • Status: Unresolved
    so now we wait, and i will post when i do receive and I did find the man’s business card which was also added. (please remember this volvo) The Truth Has Power… words never spoken enough.
56

If the above is true then explain why the sidewall of the original tires on my car say 51psi, yet the door sticker says 35psi.
Going by the above assertion there is a conflict with my original tires.

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57

That is incorrect

Again, incorrect. The max pressure on the sidewall is what the tire manufacturer rates the tire for. Not necessarily what the engineers who designed the entire car calls for. If the max tire pressure on sidewall is listed at 38 psi, then that’s what Goodyear/Michelin/Firestone/etc. says the tire can structurally take (plus a safety margin). It does not mean that that the tire should be inflated to 38 psi in all scenarios. If that tire was installed on a car that called for 30 psi on the placard, then the tire should be inflated to 30 psi, not 38 psi. That’s what the manufacturer’s specs calls for in that hypothetical situation.

Not only rough, but dangerous, I’m surprised a dealer would willfully take on that kind of liability.

Doubtful. Grossly over inflating your tires ( +10 psi over manufacturer’s specs) will result in uneven wear. 3-5 psi over is considered okay in most situations, but going much more over than that isn’t beneficial from a handling or wear perspective.

I will add a caveat to this though. If you’re driving a truck with light truck (not passenger) tires. Then it’s very possible that 50 psi would an appropriate tire pressure if you weren’t carrying a heavy load. LT tires can go upwards of 80psi, but many people will air them down to around 50 when they aren’t carrying a heavy load in favor of a more forgiving ride.

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58

I’ll pile on as well. This is completely wrong. No one else reading this nonsense should do this.

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59

Exactly!
Reading “maximum” pressure and misinterpreting “maximum” as a desirable or correct tire pressure is simply wrong.

If his doctor told him that he/she didn’t want to see blood pressure that was more than… let’s say… 140/90, that wouldn’t mean that the MD thinks 140/90 is desirable or healthy. “Maximum” is very different from correct, desirable, or healthy-- whether one is discussing tire pressure or blood pressure.

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60

Check out Continental’s recommendations on this page… scroll down to read:

“Find the handbook. Identify the manufacturer’s recommended pressure for the front and rear tires of your particular vehicle.”

And from Toyo…

“For inflation pressure recommendations for the original equipment (OE) size, refer to the tire information placard (T.I.P.) or owner’s manual.”

For non-standard tires… Toyo has a PDF file here…

Which states a warning IN RED…

“WARNING! The maximum inflation pressure indicated on the sidewall of the tire may NOT be
the recommended cold inflation pressure for your vehicle. Refer to your tire information placard
or owner’s manual for the proper cold inflation pressure and the recommended tire size. The tire
information placard (T.I.P.) can be found on the vehicle door edge, door jam, glove-box door, or
inside of the trunk lid.”

Straight from the tire manufacturer to our forum. Conclusion: Do NOT set cold pressures at the max listed on the tire.

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