What tire pressure do you use??????

[c10crazy]

If a tire has a 44 psi max rating, what to do you generally fill it up to?. What about a tire with 35 psi max, what do you fill that up to?.

[jorgensensc]

Here is an awesome informational site about this very subject. I found myself reading every word. Essetially the rule of thumb for great MPG and tire wear is max pressure minus 10%. Read this and you will be a better person for it. It truly enlightened me! http://www.carbibles.com/tyre_bible.html
Hope this helps some!
Shawn

[WorkinLonghorn]

Mine are rated for 80 psi so if I have a load of sand etc. I pressure up to 80.Then when I'm going to be empty for a while I go down to 40 or so otherwise the rears skid real easy. I didn't read the article because right from what you said about 10% less than max,I could see that it was in error.If I ran around empty with 72 psi I would wear out the middle of the tread and be skidding around like crazy since there is insufficient contact area.

[70c10]

What kind of tires require 80 psi????. They must be real heavy duty!

[jorgensensc]

Originally Posted by WorkinLonghorn

Mine are rated for 80 psi so if I have a load of sand etc. I pressure up to 80.Then when I'm going to be empty for a while I go down to 40 or so otherwise the rears skid real easy. I didn't read the article because right from what you said about 10% less than max,I could see that it was in error.If I ran around empty with 72 psi I would wear out the middle of the tread and be skidding around like crazy since there is insufficient contact area.

I don't know about your particular tires, but I have told many people about the 10% rule and it works remarkably well. As a matter of fact I have a good friend that has a camaro he has always run 32 psi in. He bumped it up to 38 psi and tool a trip from Houston to Dallas as he often does and noticed a 3 mpg increase in economy. He said it didn't ride as soft, but the edge wear from cornering with lower inflated tires seems to be improved and he has better wear across the tire. Maybe you have crazy offroad tires, they are all I can think of that would inflate to 80 psi. If that is the case they would undoubtedly skid around as they are not really made for street driving.
Shawn

[Longhorn Man]

I normally check the tread temperature to determine what pressure to run, and 99% of the time, i fined an even temp across the tread right at, or close to, max pressure.

[Stocker]

Originally Posted by Longhorn Man

I normally check the tread temperature to determine what pressure to run

Great idea, but I don't have a temp gauge -- about how much $$? Guess you'd check 'em hot, right after driving...

I have a couple tread depth gauges and use 'em fairly regularly. Helps to determine correct pressure by measuring uneven wear patterns.

jorgensensc, thanks for the link -- I'm gonna check that out soon.

[Longhorn Man]

it wasn't cheap, just under $100. But I use it at work for a lot of things, an infared, non contact thermometer.
The cats love it too, that little red dod is a thread to there happines, so they feel they have to kill it.

[truckdude239]

i run mine at 35 then if i load up i inflat to 45

[sdkid]

I have been told at training schools that the spec in the door post or owner manual is what to use. The spec on the tire is the max pressure that the tire can handle while driving wide open on the autobon. Don't know if thats the truth , but is what I was told at a chrysler training class.

[jorgensensc]

Originally Posted by sdkid

I have been told at training schools that the spec in the door post or owner manual is what to use. The spec on the tire is the max pressure that the tire can handle while driving wide open on the autobon. Don't know if thats the truth , but is what I was told at a chrysler training class.

THere is the problem with "tech" schools (no offense towards you). If you are running different than factory tires, or as in our case are probably missing that piece on the door post, then what are you supposed to do. By doing research and such education occurs and we understand the reasoning behind things, not just take things for face value. That is why if you take your truck and get a "tune up" from a local shop they will tune it back to factory specs and it will probably run like crap. If asked they will say" that is what the factory specs are" and most likely they won't be able to get it to run right. The pressures we run on our tirs are recommended for the softest ride, not for the best wear or mpg.

[Longhorn Man]

Originally Posted by sdkid

I have been told at training schools that the spec in the door post or owner manual is what to use. The spec on the tire is the max pressure that the tire can handle while driving wide open on the autobon. Don't know if thats the truth , but is what I was told at a chrysler training class.

The main reason this is what you are told, (the fed gov also preaches the sticker as the final word on tire pressures) this way, FORD, CHEVY... whomever, is responsible, and the feds feel a car's usefull life span is only 5 years anyways (anyone writing off a car on taxes knows this) so tire technology will only increase a little, and you are safe to go by that old info on the sticker.

Originally Posted by jorgensensc

THere is the problem with "tech" schools (no offense towards you). If you are running different than factory tires, or as in our case are probably missing that piece on the door post, then what are you supposed to do. By doing research and such education occurs and we understand the reasoning behind things, not just take things for face value. That is why if you take your truck and get a "tune up" from a local shop they will tune it back to factory specs and it will probably run like crap. If asked they will say" that is what the factory specs are" and most likely they won't be able to get it to run right. The pressures we run on our tirs are recommended for the softest ride, not for the best wear or mpg.

Look at ford and there Explorer problems 10 years ago. And if you think it was Fireston's fault, then you need to do some research. Ford was getting complaints from socker moms that there SUV rode like a truck. (duh) Against Firestone's strong warning on the subject, ford put out the word a few times to keep dropping the pressure, the result was a hot tire that would delmainate and throw it's tread.
My argument normally goes like this;
If your tires aren't OE, same make/model/size/on the same width rim... then that sticker is crap. An exadurated example is my truck... whie granted, there is no sticker, everyone agrees that tire technology is light years ahead of what it was back then. Well, it has increased a whole lot just in 10 years, you just don't know about it. Does anyone want to argue that a tire ment to have 80 PSI will work better at 32 PSI becouse the truck that's bolted to it?
My observations have noticed, that if the tire is the right width for the rim, then max press usually ends up with good temerature across the tread, and best possible MPG. Tread wear is kept even like this too.
I got this info when i was in highschool, I had to do a report (I went to tech school, so the report had to be tech related) This was worth 3/4 of our final grade, so I went all out. I was in contact with the upper level R&D guys at good year, BF-G, and Michilin. I asked them about my temperature idea, which I saw pit crews in both nascar and F-1 checking the tire temp acros the width right after the tires went over the wall after putting new ones on. They all agreed that this is the absoulte best way, hands down, no question asked.

The ONLY exception to this rule, is the corvair.

Originally Posted by sdkid

No offence. Like I said, just what i was told. I was getting more at the max pressure spec on the tire. I've never heard of lhm's method for auto tires. I do however use a similar method to adjust the rubber tracks on caterpillar rubber track tractors.

It's actually a race track thing, but it makes perfect sence. You want an even temp acros the thread, that way, you KNOW the whole trear is supporting the weight of the vehicle and not getting heated too much.

Originally Posted by racin69z

Every situation is different. The 80 psi tires are probably 10 ply 1 ton tires. When I had 35 12.50's on a 10" rim, I had to run 20 psi in the back (not loaded of coarse) to keep it from wearing the center of the tread out. I followed the truck down the road one day with 35 psi in the tires, and you could see air on the outer 3" of tread on both sides.

those tires were most likely too big (wide) for the rim.

[70c10]

Well I went out last night and checked the tires on my ZR2 and was suprised the max pressure stated was 65 psi. I checked them with my little tire gauge and they all read 32psi. I don't know how accurate my gauge is but that's like half of the max and way less than the 10% rule that was posted earlier. Maybe I should be running more psi????????? .

[sdkid]

No offence. Like I said, just what i was told. I was getting more at the max pressure spec on the tire. I've never heard of lhm's method for auto tires. I do however use a similar method to adjust the rubber tracks on caterpillar rubber track tractors.

[racin69z]

Every situation is different. The 80 psi tires are probably 10 ply 1 ton tires. When I had 35 12.50's on a 10" rim, I had to run 20 psi in the back (not loaded of coarse) to keep it from wearing the center of the tread out. I followed the truck down the road one day with 35 psi in the tires, and you could see air on the outer 3" of tread on both sides.

[truckdude239]

when i worked for sam's club most passager cars we set at 35 big trucks we runabout 65 then dualies we ran the rear at 80 and the fronts at 65. i was trained by michelin and am certified as a master tire techican though them. i've seen car where people wanted us to run the pressure up to 45 when the car calls for 35 then come back to us and wants to know why there tire only lasted 20,000 miles instaead of the 80,000 it was designed for. only thing we didn;t go by the door panel was the ford explorer which called for 26 psi we set then at 35 psi

[WorkinLonghorn]

What kind of tires require 80 psi????. They must be real heavy duty!

They are just your standard "Load Range E" 10 ply rating tires that are the standard replacement for my truck. Each tire is good for 3042 lbs.load IF they are inflated to 80 psi.But when the bed is enpty I like to have more of the tire in contact with the pavement for safety and tire longevity. I'm sure the 10% suggestion above is meant for normal passenger duty and not for a situation such as mine.