I maintain my front/rear tire pressure at 29/32, which is indicated in the
> door jam tag of my truck.
> However, the people at 'acme'lube insist on filling them to 38/40, which
> according to them
> is what .."is called for by the tire manufacturer"
> Whose guidelines should I follow?
>
> Most of the time the auto manufactures will use a lower pressure in the
tires to make them quieter and ride smoother. My tires say 44psi I tend to keep them at 38-40. The tire manufatures know what the limits of their tires are better than the auto people. This was part of the problem with the Firestone problems Ford had a few years back they ran the pressures lower than what Firestone recommended and that will cause the tires to wear unevenly and allow the side wall to be more parallel to the road which in turn allows for better odds of a blow out from the side wall if something punctures it.
The problem that was experienced with the Firestone tires with low air pressure was the excessive amount of flex, not only in the sidewall, but in the entire tire. However, it had nothing to do with punctures. As the tire flexes, it generates heat. As the heat increases, the tire slowly delaminates. Run long enough at a high enough heat level the tread separates from the tire. Try to compare it with bending an old credit card until it breaks in half. You will notice that there is considerable heat generated by this action until eventually it breaks too.
Not to get off topic but I had this happen to me with the tire blowing out and it was from a leak caused by the tire not sealing to the rim well I had for got to check it for a couple days and was doing about 70 down the road and it blew and the funny thing is I never even had a problem with the control of the truck it didn't pull or cause any control problems, but that could also be to the fact that I didn't panic and slam on the breaks and jerk the wheel to the right to get off the road. I wonder how many of the Explorers and other vehicles that flipped and rolled was caused by the driver panicking and not from the tire blowing?
Follow the recommendations from the tire manufacturer. Remember though that the numbers on the tire are the MAX pressure. You can safely run a few pounds lower to get a more comfortable ride. If you tow or haul a lot use the max pressure.
Here are the recommendations from a tire manufacturer, Goodyear, more of same at all tire manufacturer sites:
How much air should I put in my tires?
Proper inflation is the single most important part of tire care. The inflation pressure on the side of the tire is the MAXIMUM operating pressure. It is not necessarily the right inflation for your vehicle. Always use the inflation recommended by the vehicle manufacturer. You can find it in your owner's manual, posted on the edge of the driver's door, on a door post or on the inside of the glovebox door. Always check inflation when tires are COLD: when the vehicle has been driven less than a mile or one hour or more after driving. Use a good quality tire gauge. Note: It's natural for radial tires to have a slight bulge in the sidewall at their proper inflation pressure. Check or adjust inflation every few weeks, before any long trip or if traveling with a heavy load. And don't forget to check the spare. Your Goodyear retailer can answer any questions you may have about tire inflation.
Follow the sticker on the door pillar as it takes into account vehicle loading and ride comfort where the amount cast into the tire is actually Max tire pressure.
I would suggest the manufacturer's. They designed the tire to deal with expected loads at the tire pressure they specified. Running the tires at significantly higher or lower pressures for any length of time on road will cause irregular wear and an increased possibility of failure. If nothing else, I know that on MY vehicles, I get the best fuel mileage, longest tire life, and best handling when the tires are inflated to mfg. specs. Regards Dave Mundt
2 cents worth here, When a tire says 44psi max inflation at max load I cannot comfortably set tire pressure 10 to 14 psi below that. If I set the perssure to 40 psi whats is the worst that will happen? harder ride ? better handeling due to less sidewall flex ? better gas milage form less rolling resistance? better tread wear?
less traction, wear out the center of the tread...
The goal is to have the pressure even across the entire width of the tire, maximum tire patch contact, which will give even wear, and maximum traction. Too much air, you ride on the center, too little, and only ride on the edge.
Ford says 29/32 . Tire Manufacturer says 38/40 (max). I guess the midpoint between these 2 pressure guidelines is my safest bet. If there's one thing I can take from your posts is 'different strokes for different folks'. Thank you.
Always follow the tire manufacturers suggestion. If it's a standard passenger car tire it probably should be 35psi cold. Any less and you're risking the tire and your life.
Wrong, try factory rim, rear end of pickup with no load. The max pressure is fine if you carry the maximum load in the bed, otherwise the center will wear due to too much inflation for the load carried.
That is why they publish load tables for inflations for most trucks.
ok, whatever you say. I've run some 70 different trucks in 30 years and never wore the center out of a tire. But I guess your fukkin yuppie charts are smarter than real life experiences.
Myself, I stay on the upper end. You would have to be really overinflated to wear the center out. In the real world, I think you get better tread life with the higher inflations because of less sidewall flexing, and that in turn reduces the wear on the edges of the tire in turns. You get better MPG by a fairly good degree if you ran low pressures before. The tires run a lot cooler. But the ride is harsher. But it is more precise steering in general due to the lower flexing. It's a personal choice. I prefer better MPG, lower tire temps, and less sidewall flexing, and overall better tire wear over a cushy ride. If you run on the higher end, and do notice excess center wear, it's simple to let a bit out. But like Steve, I've never seen this happen on my cars or trucks. But I don't run right at the upper limits. Heck, I ran 35-38 lb's avg in my monte carlo. I run 50-55 in my truck, which is actually about normal. "stock wheels and plain jane
235x85x16 radial tires". I can go a good bit higher than that if I really wanted. In my monte carlo I really saved a good bit of gas on long trips if I ran 35-38 lb's instead of the recommended 20 sumthin...Too friggin mushy a ride for my tastes anyway...Look at all the exploders...Many ran the *recommended* pressures on the doors. What did it get them? A flipped truck after a tire blew out from gross underinflation about half the time. I think the *recommended* pressures have been upped a bit since then. I also think ford was more to blame than firestone, and I think firestone sort of got a bad rap out of the deal. No tire will stand up to the abuse of being underinflated and thusly overheated on a daily basis. On a fairly large top heavy SUV, it can be disaster. I think they used to recommend like 24?? lb's.. Thats silly....I would never run my own tires that low on anything I drive. I've never ran a radial at less than 30 lb's in my life, no matter what car. But like I said, I don't like mushmobiles. But you got it right... 'different strokes for different folks' MK
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