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Old 02-27-2014, 07:27 PM
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Why are so many vehicles ...

... delivered with over inflated tires?


"Tire pressure is often inflated to max sidewall pressure at the vehicle assembly plant to
prevent “flat spots” on tires during new vehicle shipping and vehicle storage. Inflating tires
to max sidewall tire pressure helps to preserve the integrity of the tire and reduces
potential technical issues. During pre-delivery verify and/or adjust tire to max sidewall
pressure. In addition, leave the tire at the maximum sidewall pressure during storage.
Move the vehicle periodically to avoid “flat-spotting” the tires."



http://www.wk2jeeps.com/tsb/tsb_wk2_2200214.pdf


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Old 02-27-2014, 11:18 PM
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Re: Why are so many vehicles ...

If the tire is at max pressure per the tire mfr's recommendation, I don't consider that an overinflated tire. It's properly inflated. Driving on them won't harm the tires or the Jeep.

I tow trailers all the time, so it really bugs me when I take a vehicle in for an oil change and they lower the tire pressures.
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Old 02-28-2014, 12:00 AM
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Re: Why are so many vehicles ...

Bear in mind that MAX pressure is the maximum pressure as per the manufacturer's recommendation...maximum does not mean optimal...it means its as inflated as they possibly can safely be.

Driving on tires that are inflated to the max pressure absolutely can cause irregular wear, and it alters the tire's traction as well as the vehicle's handling characteristics.
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Old 03-01-2014, 07:36 PM
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Re: Why are so many vehicles ...

Quote:
Originally Posted by Rexlion View Post
If the tire is at max pressure per the tire mfr's recommendation, I don't consider that an overinflated tire. It's properly inflated. Driving on them won't harm the tires or the Jeep.
Errrr, say what? Driving on a tire at its maximum rated PSi is properly inflated? Who the heck told you that?!?

Like SW said that is not a properly inflated tire and that will cause improper tread wear as well as other possible safety issues.
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Old 03-01-2014, 08:20 PM
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Re: Why are so many vehicles ...

if you want proper inflation, look at the sticker on your door jams. it tells you what the mfg recommended pressure is at. max air pressure IS NOT SAFE, it causes the tire to wear uneven( down the center) and will give a harsh ride with in increased chance of wheel hop
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Old 03-01-2014, 08:54 PM
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Re: Why are so many vehicles ...

Quote:
Originally Posted by JTS97Z28 View Post
Errrr, say what? Driving on a tire at its maximum rated PSi is properly inflated? Who the heck told you that?!?

Like SW said that is not a properly inflated tire and that will cause improper tread wear as well as other possible safety issues.
For decades, tire companies have acknowledged that in most circumstances tires wear slowest and best when inflated to max pressure as marked on the sidewall. This has been common knowledge for a long time. The first time I personally encountered the practice of vehicle mfrs doing lower pressures was with my 2000 Mercury Mountaineer (Explorer clone) and its Firestone tires. We all know how that ended. After Ford took it in the rear end from the media, suddenly the "proper" tire psi increased.

I'd like to point out that I said I tow almost constantly. Check out tire specs and you will find that the load rating is specified for max pressure. Reducing psi reduces load capacity. Towing a trailer generates considerably more heat and puts more load on the tires. Thus I am always having to make sure the oil change places don't drop my tire pressures and endanger my safety due to the risk of a blowout.

But even for the non-tower, running a tire at max psi is not going to endanger the tire's integrity in any way, because that tire is designed to be able to run at that psi. Let me re-word: it's not improperly inflated.

I fully agree that the ride will not be as cushy. Whether the tire wears faster in the center or not depends on several factors including vehicle weight and tire design; it is entirely possible. Wheel hop, I doubt it. Unsafe, I really doubt it; can you explain any reasons why it would be?
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Old 03-01-2014, 08:54 PM
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Re: Why are so many vehicles ...

I think is mostly due to them not wanting TPMS lights to come on.

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Old 03-01-2014, 09:32 PM
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Re: Why are so many vehicles ...

Tires - handling is a story of it's own here in North America - special in Canada.

Really nobody looks at them like they should. Car dealers? Tire dealers/shops?? Car owners?? I am originally from Germany. Every 2 years you need to get your car through an Government Inspection. Tires older than 5 years? GET NEW ONES! Your tires cracking on the sidewall and police is seeing that... ticket for each tire. I bought in 02/2012 a 2005 Ford Mustang convertible... 30,000 km on the tires. I ask the dealer to change them because there were 7 years old and the sidewalls are cracked... "NO! They are still goood for 100,000 km!..." Drove my Mustang to the tire shop... "What the heck... they have only 30,000 KM on them.. You really don't need new tires..." Yes I do! Got new tires by myself the same day by another dealer.....

Tire pressure should "always!" monitored because:
Disadvantages of Underinflation

.... An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle’s tires are underinflated by only 6 psi it could lead to tire failure. Additionally, the tire’s tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability. While 6 psi doesn’t seem excessively low, remember, it usually represents about 20% of the tire’s recommended pressure.

Disadvantages of Overinflation

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.....

You can read about it all over the internet if you like.
I have in my garage at home an air pressure tank and a tire gauge and check it myself!

....Advantages of Correct Tire Inflation

Maintaining correct tire inflation pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability and performance designed to match the needs of their vehicles. Tire deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tire inflation pressure also stabilizes the tire's structure, blending the tire's responsiveness, traction and handling......

LINK:
http://www.tirerack.com/tires/tirete....jsp?techid=72

Check it out, please...

And the question was..."Why do....."

You answered your question already. -> "....In addition, leave the tire at the maximum sidewall pressure during storage. Move the vehicle periodically to avoid “flat-spotting” the tires."

(I got a Japanese Lancer Evolution 4 in December 2013 for my son. Got shipped from Japan and nobody checked the tire pressure at all. Truck driver picked it up in Vancouver/BC to bring it to Edmonton/AB. Got a call from the storage/shipping manager. "..Your front tires don't hold the air anymore... do not know why... tires are only 1 year old....." The truck driver gave a shxx about the tire pressure, drove around with underinflated tires, bearings in the sidewalls broke and Junior needs on his EVOLUTION 4 four new tires! Shipping company does not cover "stupid behavior" of there drivers. So $1,000 on us to get this 4 tires replaced. This time the tire shop figured out right away that the car was driven with to low air pressure. "You can see the bearings on the sidewalls breaking and destroyed. What morons drove that car...?")

Mhhhhmmmm....
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Old 03-01-2014, 09:38 PM
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Re: Why are so many vehicles ...

Quote:
Originally Posted by Papaya205 View Post
Tires - handling is a story of it's own here in North America - special in Canada.

Really nobody looks at them like they should. Car dealers? Tire dealers/shops?? Car owners?? I am originally from Germany. Every 2 years you need to get your car through an Government Inspection. Tires older than 5 years? GET NEW ONES! Your tires cracking on the sidewall and police is seeing that... ticket for each tire. I bought in 02/2012 a 2005 Ford Mustang convertible... 30,000 km on the tires. I ask the dealer to change them because there were 7 years old and the sidewalls are cracked... "NO! They are still goood for 100,000 km!..." Drove my Mustang to the tire shop... "What the heck... they have only 30,000 KM on them.. You really don't need new tires..." Yes I do! Got new tires by myself the same day by another dealer.....

Tire pressure should "always!" monitored because:
Disadvantages of Underinflation

.... An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle’s tires are underinflated by only 6 psi it could lead to tire failure. Additionally, the tire’s tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability. While 6 psi doesn’t seem excessively low, remember, it usually represents about 20% of the tire’s recommended pressure.

Disadvantages of Overinflation

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.....

You can read about it all over the internet if you like.
I have in my garage at home an air pressure tank and a tire gauge and check it myself!

....Advantages of Correct Tire Inflation

Maintaining correct tire inflation pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability and performance designed to match the needs of their vehicles. Tire deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tire inflation pressure also stabilizes the tire's structure, blending the tire's responsiveness, traction and handling......

LINK:
http://www.tirerack.com/tires/tirete....jsp?techid=72

Check it out, please...
well said
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Old 03-02-2014, 09:44 AM
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Not only is papaya correct. Also when changing to a different size tire you should find out what is the optimal pressure for your vehicle.
It is not the max allowed by tire mfg, and it is no longer the pressure recommended by jeep necessarily.

It should be calculated based on the new tire parameters and jeep weight. I'm sure that the formula is out there somewhere on the WWW.
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Old 03-02-2014, 11:32 AM
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Re: Why are so many vehicles ...

Quote:
Originally Posted by bill_de View Post
... delivered with over inflated tires?


"Tire pressure is often inflated to max sidewall pressure at the vehicle assembly plant to
prevent “flat spots” on tires during new vehicle shipping and vehicle storage. Inflating tires
to max sidewall tire pressure helps to preserve the integrity of the tire and reduces
potential technical issues. During pre-delivery verify and/or adjust tire to max sidewall
pressure. In addition, leave the tire at the maximum sidewall pressure during storage.
Move the vehicle periodically to avoid “flat-spotting” the tires."



http://www.wk2jeeps.com/tsb/tsb_wk2_2200214.pdf


---

That's interesting, because when I picked up my WK2 the low tire light was on and every tire was 6lbs too low. Talk about a thorough pre-delivery inspection. The dealerships response. The "cold" must have done that.
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Old 03-02-2014, 12:22 PM
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Re: Why are so many vehicles ...

Here in the Edmonton, Alberta Canada area with -30 Celsius and deeper temps, the low air pressure warning comes on also you had the right tire pressure before. So the outside temps are really lower the tire pressure! Driving at 30 mph/50 kph for 5 minutes and the light goes out and the tire pressure is green again.... warming up the air when driving. We learned that with our Dodge Journey in 2012... same issue in the winter but normal.

http://www.accuweather.com/en/weathe...her-on-t/41518
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