I've seen several threads on tire pressure, but not this topic. I have a '98 Mazda B3000. The door plate tells me to run 30psi in all four tires. The owners manual says 35psi. That is a pretty wide gap. Which one would anyone suppose is correct? I've been running 32-33psi since I bought the truck in Sept. of 03. Rarely haul anything heavy. I just like the truck and pretty much to and from work (about 6 miles each way) is what I use it for. Occasionally we'll use it for a day trip, usually under 75 miles one way. Thanks for any info.

 

The pressure on the door tag is what got the Exploders in trouble! Ford in all their wisdom is trying to sell TRUCKS to soccer moms.. So they have a tire pressure that will give a smooth ride. Even though the little fellas have TRUCK springs in them.. So what to do?
I'll tell ya who has the best sayso in the matter. The tire manufactor is who. Look at the small wording on the tire itself and it will give you the rating of the tire in PSI. I ALWAYS go with that and never even look at the door tag!
That door tag KILLED lots of good folks in the past few years.
Too low of a tire pressure will overheat the tire and give unexpected results.
Big Jim

 

Big Jim M - I hate to say it, but this is just bad advise, and only partially based in fact.

While the Explorer tragedies were just that - tragedies: Ford was not the only one to blame poor quality control on Firestone's part, and owner's not checking tire pressure AND driving too fast heated up the tires and exploited the weakness.

The markings on the side wall of your tires are for "MAX" capacity. IE - an OE tire may say on the sidewall that it has a MAX PSI of 44, at a MAX load of 1250 lbs. While the mfgr of the car will have a sticker that says 32 PSI. This is mainly based on the fact that the weight of the vehicle is generally only going to account for ~60-70% of the MAX tireload. Which also means that the PSI should not be set anywhere near the MAX.

ALL car manufactures have door stickers that read less than the sidewall of the OE tires.

One thread:
https://www.ford-trucks.com/forums/s...d.php?t=348382

 

Howdy G2IC_Wraith
We could each expand upon our opinions of this for hours and hours if you wish... Those firestone tires were on many makes of vehicles and Ford was tha only one with problems... The reason was the recommended pressure.
And yes the owners were not, for the most part, as aware of their rides as you and I and most here are.
If you take the average citizen and tell him 26/28 lbs is the number he will put that in there and about 11 months later he will load up with 7 adults and load the top rack with another 450 lbs of luggage and start out from there.
BUT if you tell him to read on the tire and put the max in there... 11 months from now there may still be an allowable amount in there.
As far as the center wearing faster on these steel belted radials... I cannot see how.
I do see a bias ply tire needing the exact amount of air or it will donut and wear either the middle or the edges of itself..
I cannot see anyone getting themselves in trouble using the maximum amount of air in their tires..
Big JIm

 

I am sorry if you feel this is a debate. I assure you it is not. It is a matter of facts.

Fact 1) Tires DO wear down the center when over inflated regardless of composition.

Fact 2) Tire sidewall markings are a reference for MAX PSI, at MAX Load. IE - a given tire with markings of 44psi, 1450lbs: This means that this is the spec to use in order for the tire to maintain proper contact with the road, and support the load.

Fact 3) Driving with over inflated tires is VERY dangerous. There is not enough contact with the road to maintain control, and the vehicle will feel like it is running on solid tires.

Fact 4) Tires that come OE on ALL cars and trucks are selected because they can handle 25%, or higher, load than the base vehicle.

Fact 5) Rangers base weight IS less than the load capacity of the tires you will put on there. If an owner does not understand that tire pressure should be checked/adjusted according to temps and load they should not even turn the key.

Contradicting a manufacturer because you feel you know better is one thing. Advising others to follow misguided fears is just irresponsible. The only reason for failure was NOT Ford's recommended pressure in the Explorer. The formula for disaster was:
Ford trying to smooth out the ride on a poor suspension by lowering tire psi + Poor Firestone quality control + Drivers driving a GIANT SUV like a car = disaster

larpa - The psi you have been running should be fine as long as you don't see center wear, and feel like you are driving on ice skates. I believe most Rangers and B series have the 30psi on the door.

 

The only reason for failure was NOT Ford's recommended pressure in the Explorer. The formula for disaster was:
Ford trying to smooth out the ride on a poor suspension by lowering tire psi + Poor Firestone quality control + Drivers driving a GIANT SUV like a car = disaster

My point ya see is that not only the Explorer but many of our vehicles have intentionally low advised pressures just to sell the soft ride. The little trucks should NEVER have worn a metric shaped tire. Them are trucks and should have had a LT tire from the beginning.
Try as hard as I can I cannot see a steel belted tire that has worn in the middle.. I see them all the time worn on the sidewall from to LITTLE air. I have seen bias-ply that were center worn in the past but never a radial. Might be because of the amount of air being carried by most folks.
I can see where a cautious, politically correct person would hesitate to advise this or that to others. I do not fault you for that. However my experience leads me to think and firmly believe that the maximum will get you out of more trouble than it will get you into.
Big Jim

 

If someone is to assume what you are saying is true, then you are implicating the entire automaker industry in a conspiracy theory (not just Ford). Most EVERY end consumer vehicle will have a door sticker with a recommended PSI lower than what the OE tire's sidewall says.

There is a reason for this: If you ask an engineer (from an auto maker, not buba at the tire store) why you will get a lot of verbal fluffing, but the conclusion is the recommended PSI is calculated based on the standard load the vehicle will be putting on it. Can you adjust that recommendation +/- a few PSI.... sure. But no one should be daily driving on MAX PSI filled tires.

Just because you have never seen first hand tires worn down the center does not mean it doesn't happen. Spend some time looking at cars coming in for alignments and you won't go a week with out seeing it.

I am not sure where you get the idea that Rangers should have come with LT tires OE. By the tire manufactures standards our trucks are not big enough nor can they carry the load an LT tire was designed for.

100% False. This is just as dangerous, only in different ways. Unstable handling and high speed maneuvers will cause a roll over, prone to hydroplane on wet roads, wear down the center, rough ride and excess suspension wear, etc...... It is not about being a "politically correct person" it is ALL about your safety and those around you. I am one of the most politically incorrect people out there - FYI.

 

if its a stock size tire then the psi you are running at is fine. If you haul something heavy then pump up the tires to the max rating on the sidewalls of the tires. I have 31x10.5x15 on my truck and run them 40 psi at all times. If you don't mind a rough ride you can leave the tires at max psi for better gas milage but the tires might wear funny if the truck isn''t loaded down.

 

It is strange that the manual and door do not agree, I'll check mine. I assumed the manual said to consult the door sticker..

I concur with G2IC for the most part. The ride is bad enough at recomended PSI, I cant imagine how bone jarring it would be at 45 or 50 (or more dep on your tire rating) unloaded.

My door says 30F/35R by the way.

 

I wonder if the reason for the discrepancy is most owner manuals do a blanket coverage of 3 or 4 different models ( edge, XLT, 4x4, 2wd ). Stick with the door tag, it is specific to YOUR vehicle.

 

This is very possible. The other instance I remember reading about was Mazda trucks leaving the factory with Ranger stickers and markings. Other than that if the Mazdas came with a different OE tire it may have had a different load rating that would warrent a pressure change. While 5psi is not a ton, it still needs to be watched.

 

I had a pair of Blizzaks that wore VERY badly in the centre due to too much air pressure. They were 235's instead of the 225's that came on the truck and I didn't lower the tire pressure accordingly. Granted the Blizzaks will exagerate any tire pressure error, but I assure you it's quite possile to wear the centre of a tire out due to too much pressure.

For the record, my '98 B2500 reccommends 35 p.s.i. front and rear. They came with the Firestone Wilderness HT 225/70/14 tires.

 

Tortoise: You say your '98 B2500 calls for 35psi front and rear. Is that the owners manual or the door tag???

 

my bad. The figure came from the door. But I am pretty sure the door of my truck is consistent with the owner's manual.

 

Just for my two cents on the matter, when a manufacturer makes a tire, they give it a generic name and specs, rather than "Tires-for-this-model-make-weight-etc.". Then they can use it on more than one car. When Ford, or anyone for that matter, chooses a tire for a vehicle, they do a lot of tests on how a tire will act on it (I've seen some of the tire bounce range files... crazy stuff!) and factor a lot of things in, such as weight of the vehicle, then choose the best tire at the best inflation. It's my opinion that the Ford/Firestone deal was just someone's bad judgement when they didn't think about worst-case-scenario matters. That aside, just go with what's on the door. Think of it like eating... your stomach also has a MAX, but do you think it's best for you to run it at full capacity all the time? Okay, not exactly the same, but a funny thing to think about nonetheless...
Oh yeah, and I think LT tires are not necessary on Rangers... maybe some people would benefit from them if they haul/tow a lot, but they're not meant for light passenger trucks. They're meant more for tough applications.