Truck tire pressure

[milkman636]

...............I also find it a bit funny that people say you should never trust the manufacturer of the vehicle to know what they are talking about because of one bad example. I would hazard a guess that because of the liability involved, most of the time, the vehicle manufacturer is going to recommend a pressure that is well above a range that would endanger the tire and thus the car, and then lead to a lawsuit - again.

Just my 2.1｢.
Dave

Its not about trusting them. Its just that the manufacturers have to pick a single compromise number for tire inflation that suits every operating condition that your truck will experience within its design parameters. They have hours of meeting where groups of engineers discuss why their number is the best. Then they settle on a compromsied specific number. That's one of the reasons new vehicles cost so much. We simple minded:confused2: owners can't be trusted to make our own judgements about loading and tire pressures.

 

[Egon]

You shouldn't forget that a tire that is inflated to a higher pressure has a smaller footprint and that means less braking ability./QUOTE]

According to some long ago physics the contact area does not matter.

 

[JasG]

You shouldn't forget that a tire that is inflated to a higher pressure has a smaller footprint and that means less braking ability./QUOTE]

According to some long ago physics the contact area does not matter.

Going by this in dry PSI have very little impact, but wet higher PSI can be better. Basically in dry condition you are correct it doesn't seem to matter.


The braking distance is at the bottom with comments about the findings.
TIRE PRESSURE SURVEY AND TEST RESULTS

 

[oldyellr]

You shouldn't forget that a tire that is inflated to a higher pressure has a smaller footprint and that means less braking ability.

According to some long ago physics the contact area does not matter.

I remember that too and believed it at the time. But that was before tire technology was developed to where acceleration, cornering and braking forces started to go above 1 G.

 

[Reg]

Going by this in dry PSI have very little impact, but wet higher PSI can be better. Basically in dry condition you are correct it doesn't seem to matter.


The braking distance is at the bottom with commenst about the findings.
TIRE PRESSURE SURVEY AND TEST RESULTS

Where it MATTERS is when there is standing water on the road.
Lower pressure translates to larger area, leads to easier hydroplaning - at which point braking and steering are GONE AWAY.
This is why WIDE tires are such a bad choice, they LIFT too easily on water.

 

[Egon]

Thanks for the information JasG.:thumbsup:

 

[JasG]

Thanks for the information JasG.:thumbsup:

Your welcome.

 

[zzvyb6]

Sorry to have to correct some misinformation here, but the EPA now pretty much sets the required pressure in all car and truck tires because of rolling resistance (fuel economy) demands. Requirements are set by a coast-down test which is then used to recreate the roadway conditions on a chassis dynomometer.

Stopping distance effects are not an issue because the tire construction recipe is then established by the tire manufacturer in order to meet dry, wet and sometimes snow traction requirements of the tire for braking and traction in order to meet MVSS105 stopping distance requirements. These are requirements set by Federal Law, not some arbitrary committee at a vehicle design or marketting meeting. Additional tire properties are set by design if ABS is used to meet stopping distance.

That's why I only buy OEM tire manufacturer brands. Its no secret in the industry that off brand tires have dismal performance for rolling resistance, traction, durability and longevity. If low cost is your need, low performance comes along with it. Amongst these brands, only the models with certain key symbols on the sidewall actually are equal to the OEM tires. GM's TPC, BWM star and Mercedes codes are well known.

 

[oldyellr]

Sorry to have to correct some misinformation here, but the EPA now pretty much sets the required pressure in all car and truck tires because of rolling resistance (fuel economy) demands.

That likely explains why the door pillar tire pressure numbers on today's cars are higher than they used to be 40 years ago and why a lot of "old timers" never trust those numbers and use the maximum sidewall number instead.

 

[xtn]

Sorry to have to correct some misinformation here, but the EPA now pretty much sets the required pressure in all car and truck tires because of rolling resistance (fuel economy) demands. Requirements are set by a coast-down test which is then used to recreate the roadway conditions on a chassis dynomometer.

Stopping distance effects are not an issue because the tire construction recipe is then established by the tire manufacturer in order to meet dry, wet and sometimes snow traction requirements of the tire for braking and traction in order to meet MVSS105 stopping distance requirements. These are requirements set by Federal Law, not some arbitrary committee at a vehicle design or marketting meeting. Additional tire properties are set by design if ABS is used to meet stopping distance.

That's why I only buy OEM tire manufacturer brands. Its no secret in the industry that off brand tires have dismal performance for rolling resistance, traction, durability and longevity. If low cost is your need, low performance comes along with it. Amongst these brands, only the models with certain key symbols on the sidewall actually are equal to the OEM tires. GM's TPC, BWM star and Mercedes codes are well known.

It is my experience that OEM tires are not the absolute best available at all. They certainly aren't the worst choice and you could do a lot worse, but if you research you can do a lot better too.

But of course "better" totally depends on the qualities that you value as an owner. Better dry grip? Better longevity? Better NVH? Better foul weather performance?

On my car I choose to give a high value to dry grip, a secondary value to turn-in feel, a distant third value to longevity, and almost no value at all to any other quality. Therefor I choose an 'R-comp' DOT legal tire with a 60 treadwear rating that I like the feel of. If your criteria are different than mine you would hate this tire. I get about 4,000 miles out of a set, they have a lot of rolling resistance, they hydroplane at the drop of a hat, are not much good below 50degF or when driven in the rain and when used hard they sling little drops of rubber up onto the body of my car. By by my personal standards for that particular car and what I expect out of driving it, they are "better" than any other choice.

So depending on one's usage and criteria, OEM is not automatically the best. My aftermarket tires stick better, are faster around the track and cost less than OEM.

xtn