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Old 05-30-2006, 12:13 PM   #1
Tankota
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Have you even realy read what it says on the tire? The pressure listed on the tire itself says "maximum". Not suggested, not even what tire pressure it should be set. It only lists the maximum. Tire manufactures have no idea what car the tire will be used on, what the weight load on the tire will be, or anything else. All the listings on the tires are the max load, max tire pressure, and max speed the tire has been tested to. Nothing at all to do with the tire in real world use on a vehical. That pressure is set by vehical for that size tire. And it's listed on the door. And yes, if you inflate that tire to the maximum listed on the tire, and you are not using it on a vehical that is at the max weight listing on the tire, it's overinflated.

And yes, Toyota are recomending the settings for safty.. not overinflating the tire, not underinflating the tire. They are listing the correct, safe tire pressure for that size tire, regaurdless of who makes it. That pressure will provide the max traction, cornering, stopping, and acceleration. If you overinflate it by doing what you suggest, inflating a tire to it's max tested PSI, then you will lose some if not all of this. For what, 1-2 MPG? Maybe? You won't find much a diffrence in MPG overinflating a tire. You can lose some by underinflating a tire. And it's very unsafe to be running around on tires inflated to the max listed on the tires.

Quote:
Originally Posted by why?
Toyota engineers are recommending settings for 1 thing only - safety. They have to assume everyone that drives the car shouldn't really have a license, so they have to make all settings super-conservative so that the morons don't kill themselves and Toyota doesn't get sued.

No one ever recommended over-inflating tires.

Tire manufacturers know more about their tires than Toyota does. They know what is safe, and what the tires will handle.

Using the maximum pressure of a tire will not cause uneven tire wear as the manufacturers have created the tires to run at that setting.

It is always best to trust the manufacturers of a component over the manufacturer of the entire car.
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Old 05-30-2006, 12:29 PM   #2
why?
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Quote:
Originally Posted by Tankota
Have you even realy read what it says on the tire? The pressure listed on the tire itself says "maximum". Not suggested, not even what tire pressure it should be set. It only lists the maximum. Tire manufactures have no idea what car the tire will be used on, what the weight load on the tire will be, or anything else. All the listings on the tires are the max load, max tire pressure, and max speed the tire has been tested to. Nothing at all to do with the tire in real world use on a vehical. That pressure is set by vehical for that size tire. And it's listed on the door. And yes, if you inflate that tire to the maximum listed on the tire, and you are not using it on a vehical that is at the max weight listing on the tire, it's overinflated.

And yes, Toyota are recomending the settings for safty.. not overinflating the tire, not underinflating the tire. They are listing the correct, safe tire pressure for that size tire, regaurdless of who makes it. That pressure will provide the max traction, cornering, stopping, and acceleration. If you overinflate it by doing what you suggest, inflating a tire to it's max tested PSI, then you will lose some if not all of this. For what, 1-2 MPG? Maybe? You won't find much a diffrence in MPG overinflating a tire. You can lose some by underinflating a tire. And it's very unsafe to be running around on tires inflated to the max listed on the tires.

Tire manufacturers know their tires better than car manufacturers do.

And if you knew anything about tires, you'd know that tires are so different that no 1 pressure would work for all types of tires of the same size, never mind tires of different sizes.

If you look around this forum, you will see the majority of people modifying their cars. They do this for a reason, because the manufacturer of the vehicle simply does not know how everyone will use their vehicle, or what everyone wants in a vehicle.

Tires and tire pressure are no different. Toyota recommends a safe lawsuit free pressure that won't hurt anyone. Well, as long as you use the car exactly how Toyota wants you to, meaning always doing the speed limit, never pushing the car very hard, etc, etc.

If you use the vehicle any different than that then Toyota's recommendations are worthless to you.

Using the maximum pressure in a tire is NOT "overinflating". Using more than the maximum is.


"And yes, if you inflate that tire to the maximum listed on the tire, and you are not using it on a vehical that is at the max weight listing on the tire, it's overinflated."


This has to be one of the dumbest things I have ever seen written. If you're running tires at their max weight listing your just asking to die. Every bump in the road, every single hill, every corner you takes adds pressure to the tires, and if you are running a tire so weak that your vehicle's weight is maxing the tire out, the tires will fail spectacularly.

If everyone thought like you did no one would ever modify anything, or use anything other than the way manufacturers want them to.

Rofl, that just isn't going to happen.
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Old 05-30-2006, 01:09 PM   #3
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Ok, I see this isn't going to get through to you. A simple search on the internet will show you that you don't run tires at the max listed on the tire, unless you are at the maxium load on them. The tire is tested to run at these limits and not fail (even hitting bump). But it does not mean you should use that air pressure for every application.

Since you brought up modifing cars, do you even know how to test for proper pressure on a modifed vehical for diffrent conditions? No? I do, I do this all the time and I can bet I know more about tires, pressure, traction, and control than somebody that says to use the maximum pressure listed on a tire. Do you know how much pressure needs to be incresed for plus 1 size, plus 2 size, etc over stock? Do you know that given the same size and rated tire, the only diffrence in the needed air pressure in the tire is how much load is on that tire, no mater who makes it?

There is a proper pressure for a tire with a specfic load on it. and you claim the tire manufacture knows more, and knows exactly what car and what the weight of that car it's going to be used on it.. They must be realy smart then and have that sidewall change numbers depending on what car it's put on, sound like Magic to me! So yes, the car manufacture does know more, they know exactly what car and what that cars weight on that tire will be, and thus they know the correct pressure.. If you can explain to me how the tire manufacture can know this for their tires, which can be used on all diffrent cars, and can possible adjust this sidewall number magicaly???

As for my dumb statement, you are the one suggesting using the maxium air pressure listed on the tire, because tire manufactures know their tires more, and that's what they are desigend to run at..?? The letters "Max" on the tires are still not getting through to you.

Before we go any further with this, kindly do some simple searches on the internet on tire pressures, reading sidewalls, proper air pressures, and the effects of pressure and load on tires and their shape, and wear.

Besides which, this is all overkill for this forum. All people need to know is that the best tire pressure for that size tire on the car is listed on the door, you can go up to 5psi higher than this if you like, and that going over that or under the recomended can have adverse and in fact unsafe results. And DO NOT use the max listed on the tire. End of story.

Quote:
Originally Posted by why?
Tire manufacturers know their tires better than car manufacturers do.

And if you knew anything about tires, you'd know that tires are so different that no 1 pressure would work for all types of tires of the same size, never mind tires of different sizes.

If you look around this forum, you will see the majority of people modifying their cars. They do this for a reason, because the manufacturer of the vehicle simply does not know how everyone will use their vehicle, or what everyone wants in a vehicle.

Tires and tire pressure are no different. Toyota recommends a safe lawsuit free pressure that won't hurt anyone. Well, as long as you use the car exactly how Toyota wants you to, meaning always doing the speed limit, never pushing the car very hard, etc, etc.

If you use the vehicle any different than that then Toyota's recommendations are worthless to you.

Using the maximum pressure in a tire is NOT "overinflating". Using more than the maximum is.


"And yes, if you inflate that tire to the maximum listed on the tire, and you are not using it on a vehical that is at the max weight listing on the tire, it's overinflated."


This has to be one of the dumbest things I have ever seen written. If you're running tires at their max weight listing your just asking to die. Every bump in the road, every single hill, every corner you takes adds pressure to the tires, and if you are running a tire so weak that your vehicle's weight is maxing the tire out, the tires will fail spectacularly.

If everyone thought like you did no one would ever modify anything, or use anything other than the way manufacturers want them to.

Rofl, that just isn't going to happen.
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Old 05-30-2006, 04:11 PM   #4
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The above posts were taking the Fuel Economy thread way off-topic so they've been moved to a new thread.

KEEP IT CIVIL FOLKS.

Thanks

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Old 05-30-2006, 04:32 PM   #5
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Quote:
Originally Posted by YarisBueller
The above posts were taking the Fuel Economy thread way off-topic so they've been moved to a new thread.

KEEP IT CIVIL FOLKS.

Thanks


Ok, sorry ... It did start in the context of tire pressure and fuel economy.. just went into a tad more detail.. BTW some of the direct posts and replies to this part are missing, so a lot of this is out of context now?
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Old 05-30-2006, 04:56 PM   #6
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All tires have to meet certain standards. I was watching this show on how all tires are tested, and they are all pumped up with way more PSI than they should be, and run at 300km or something crazy like that. If they don't pass this test they can't be sold. So I'm pretty sure that over-inflating them like 5-10PSI won't do much except make you have better mileage (debateable) and a rougher ride.
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Old 05-30-2006, 05:39 PM   #7
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Again, I agree with Tankota. The Max measurements are pretty much useless outside the context of the vehicle - the weight, the width of tire being used, suspension geometry, style of driving, etc. - all play a part in what amount of inflation you should use. Saying that you should just use the max is ridiculous.

And as I said in the other thread, having the Yaris' stock tires above 40psi in my experience results in a loss of traction - to a dangerous extent for an unskilled driver, imo. Using the max of 44psi would be pretty stupid.
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Old 05-30-2006, 06:01 PM   #8
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It still would be interesting to do a test with folks here. Have folks fill their tires with different air pressures and see is there is any difference in gas milage.
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Old 05-30-2006, 06:08 PM   #9
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Quote:
Originally Posted by foober
It still would be interesting to do a test with folks here. Have folks fill their tires with different air pressures and see is there is any difference in gas milage.
It wouldn't really tell you anything since we all live in different locations with different road conditions, different fuel and different driving styles. A better test would be having someone try a different setup on a predictable commute over time.

I can tell you that on our Prius, proper inflation makes a huge difference, as does the tire. We just had our tires replaced to a non-OEM tire, and we're getting about 6mpg worse gas mileage now. :(
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Old 05-31-2006, 01:57 AM   #10
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Same thing happened to me:

Tires inflated at 28/29psi = about 8-10 less mpg on MY Yaris.

The tires were underinflated for an 1100km trip I took and I lost about 10 mpg off of my original 3 fills on the same highway.

The same happened when I overinflated them, though not too the same extent...I also found the car to be quite 'bouncy' to describe it...I know not much about traction control or anything like that, but I do know MY Yaris felt a little uncomfortable at that psi.

I check my tire pressure at least weekly, and have every tire at EXACTLY 32 psi, and get 40-45 mpg in the city, and 45-55mpg on the highway.

End of story as far as I'm concerned.
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Old 05-31-2006, 08:53 AM   #11
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Quote:
Originally Posted by NickNickNick
Same thing happened to me:

Tires inflated at 28/29psi = about 8-10 less mpg on MY Yaris.

The tires were underinflated for an 1100km trip I took and I lost about 10 mpg off of my original 3 fills on the same highway.

The same happened when I overinflated them, though not too the same extent...I also found the car to be quite 'bouncy' to describe it...I know not much about traction control or anything like that, but I do know MY Yaris felt a little uncomfortable at that psi.

I check my tire pressure at least weekly, and have every tire at EXACTLY 32 psi, and get 40-45 mpg in the city, and 45-55mpg on the highway.

End of story as far as I'm concerned.
I agree on keeping them at 32psi but if you are getting 45-55mpg you are not doing your gas calculation correctly. There is no way possible you are getting that MPG. EPA mpg are normally a little high and the best they give on the Yaris is 39/40.

Kevin
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Old 05-31-2006, 11:00 PM   #12
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LAst two trips:

710km/33L of fuel

654km/35.5L of fuel

What does that work out to?
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Old 05-31-2006, 11:59 PM   #13
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710km/33.0L = 4.65L/100km or 50.90 mpg (U.S.)
654km/35.5L = 5.43L/100km or 43.58 mpg (")

If these numbers are correct you should be very happy. Maybe you could go into detail into the driving that was done during these two tanks.
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Old 06-01-2006, 03:32 AM   #14
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I drove across the prairie provinces on a flat divided highway with speeds ranging from 90-130km/hr.

5th gear all the time, except to pass when I'd drop to 4th.

I filled my washer fluid once along the way.
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Old 06-01-2006, 03:38 AM   #15
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31L on 478kms.

In the city.
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Old 06-01-2006, 09:04 AM   #16
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Quote:
Originally Posted by NickNickNick
31L on 478kms.

In the city.
478km/31L = 6.49 L/100km or 36.48 mpg (U.S.)
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Old 06-01-2006, 09:31 AM   #17
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NickNickNick, check Fuel enco page, there is all sorts of calculators people posted.
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Old 06-01-2006, 12:47 PM   #18
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I have used these fuel calculators.

I have calculated my fuel economy.

Letting other people do it for me allows them to see the mileage I get, and that it has been anywhere from 35mpg in the city to 55mpg on the highway.
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