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Old 5th April 2005, 23:48   #46
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Here's what a website had to say....
Quote:
Tyre Pressure
Check the tyre pressure of your car once a month

An important part of the energy for propelling a car is needed to overcome the rolling resistance of the tyres. 25% too low tyre pressure increases rolling resistance by 10% and fuel consumption by 2%. Too low tyre pressure also has unfavourable effects on vehicle handling and braking distance.

To ensure correct tyre pressure, you need to check your car's tyres at least once a month. Tyre pressure must be checked at cold tyres. This means that you have driven less than three kilometres, otherwise you have to wait for about 10 minutes to let the tyres cool down. Car manufacturers always recommend two different tyre pressures: one for driving unloaded and/or mainly at normal speeds and one for driving fully loaded and/or mainly at high speeds. These pressure indications can be found in the instruction manual, but often also on a label at the door post or at the fuel filling flap of your car.

Nowadays newly sold passenger cars of several makes are already equipped with an electronic system that continually monitors the tyre pressure. Such systems can also be fitted in as an accessory in other cars.
Link

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Last edited by Shan2nu : 6th April 2005 at 00:00.
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Old 5th April 2005, 23:57   #47
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Quote:
Originally Posted by Shan2nu
Here's what a website had to say....

Shan2nu
lol... dat was fast...

Last edited by amitoj : 6th April 2005 at 00:05.
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Old 5th April 2005, 23:58   #48
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The thing is that, using lower tyre pressure increases rolling friction and if you have a tube inside, there is bound to be friction between the tube and the tyre as well.
Perfect. The single most reason for blow outs. Many people have the misconception of reducing the tyre pressure before embarking on expressway. Wrong! Seriously wrong!!
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Old 6th April 2005, 00:03   #49
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Probably the only place where lower tyre pressure is recomended is on sand. This increases the contact patch reducing the weight per square inch.

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Old 6th April 2005, 06:01   #50
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Originally Posted by RJK
Perfect. The single most reason for blow outs. Many people have the misconception of reducing the tyre pressure before embarking on expressway. Wrong! Seriously wrong!!

i think reducing the tyre pressure by about 1 or 2 Psi is ideal. Coz the tire pressures giving by the company is for normal city driving. It is very important to reduce ur tire pressure by about 1 Psi depending on the amount of ppl u are carrying with u in the car. and yeah also depends on the way u drive!!!
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Old 6th April 2005, 10:15   #51
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hey Jigar,

lesser tire pressure means:

1.higher fuel consumption
2.greater contact area of the tire with the road,so that means greater rolling resistance.which in turn means more load on the engine.
and,

3.since we are talking about expressway speeds,its simply foolish to reduce the pressure.



and with more people on board,u should increase the tire pressure and not reduce it.


read this


Quote:
Originally Posted by http://www.starfiretires.com/us/en/safety/tireSafetyInstructions.asp#item3

Correct Tire Pressure

Correct tire pressure is very important. Driving on any tire that does not have the correct inflation pressure is dangerous. Proper inflation pressure for your tires may be found in the vehicle owner's manual or the vehicle's tire information placard.

Any underinflated tire builds up excessive heat that may result in sudden tire destruction.

Refer to the tire placard on the vehicle (check vehicle and/or vehicle owners manual for placard location) for the recommended operating pressures. These pressures must be maintained as a minimum. Do not exceed the maximum pressure indicated on the tire sidewall of passenger car tires.

If you are replacing the original size tires with tires of a different size, you must consult a knowledgeable dealer to determine the correct inflation pressure for your new tires. If you need additional help, or still have questions, call us at 1-800-854-6288.




Checking Tire Pressure

Check tire inflation pressures (including the spare) at least once a month when tires are cold and before long trips.

Failure to maintain correct inflation may cause rapid and irregular tire wear, sudden tire destruction and may result in loss of vehicle control and serious personal injury. Therefore, inflation pressures should be checked atleast once a month and always prior to long distance trips. Any tire is susceptible to losing air pressure if not properly maintained.

Pressures should be checked when tires are cold; in other words, before they have been driven on. Driving, even for a short distance, causes tires to heat up and air pressure to increase. Tires run even short distances while severely underinflated may be damaged beyond repair.




High Speed Driving

High speed driving can be dangerous.

Correct inflation pressure is especially important. However, at high speeds, even with the correct inflation pressures, a road hazard is more difficult to avoid and if contact is made, has a greater chance of causing tire damage than at a lower speed. Moreover, driving at high speed reduces the reaction time available to avoid accidents and bring your vehicle to a safe stop.

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Old 6th April 2005, 11:53   #52
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I feel one should maintain lower pressure.

Let's say 28 instead of 29. Even if we assume now that, it causes more friction and heats up quicker (I am not sure it would by such a small change in pressure), the pressure will increase from 28 to 29 psi and then further increase. So, ideally it should never create any problem.

On the other hand, if you add 2 more psi to 29 before starting. Chances are that, it will quickly blow up because there is not much pressure rise that tyres can sustain.

Does it make sense?
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Old 6th April 2005, 12:07   #53
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Let's say 28 instead of 29. Even if we assume now that, it causes more friction and heats up quicker (I am not sure it would by such a small change in pressure), the pressure will increase from 28 to 29 psi and then further increase. So, ideally it should never create any problem.

On the other hand, if you add 2 more psi to 29 before starting. Chances are that, it will quickly blow up because there is not much pressure rise that tyres can sustain.

Does it make sense?
Nope, it doesn't make sense since a 30 psi tyre would have reduced it's contact patch, reducing rolling friction in the process.

And don't think that tyre blowouts are caused only by pressure increase. In most cases it's the strain on the tyres that cause them to b'com weak and prone to blowouts.

With every psi reduction in tyre pressure, you're adding that much more load/strain on the sidewalls. usually tyres can sustain upto 44 psi of pressure before they give way but, this holds weight, only when the tyres are properly inflated.

Running a lower pressure reduces the tyres ability to sustain high pressure and can cause the tyre to blowout well within the specified limit of 44 psi.

A tyre can only work effectively when filled with the right tyre pressure.

No authorised website will recomend lowering the tyre pressure when driving on an expressway, where high speeds are maintained for a long period of time.

Shan2nu

Last edited by Shan2nu : 6th April 2005 at 12:47.
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Old 6th April 2005, 12:19   #54
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Says Mumbai-based tyre expert Sujon Chaudhuri of International Tyre Service: “The minimum depth of the tread of your car tyres should be 1.8mm, since bald or ‘slick’ tyres, though great for the race track, will not have adequate grip on roads, specially on slippery surfaces like water etc. Radial tyres that look perfectly ‘healthy’ from the exterior but are more than five to seven years old should not be used at high speeds, if used at all, since they would have become weak from inside due to belt distortion. Also, it is inadvisable to go in for locally resoled tyres as they may not be uniformly resoled, resulting in disparate weight distribution. While you should always maintain the manufacturer’s recommended tyre pressure, it is advisable to increase pressure a bit before going onto a fast-paced, long drive since the higher pressure prevents excessive flex, thus preventing a blow-out.”
Source : http://www.indiacar.com/index2.asp?p..._insurance.htm
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Old 6th April 2005, 12:29   #55
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While you should always maintain the manufacturer’s recommended tyre pressure, it is advisable to increase pressure a bit before going onto a fast-paced, long drive since the higher pressure prevents excessive flex, thus preventing a blow-out.”
There you go!!!

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Old 6th April 2005, 12:40   #56
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okay ...thats made things a lot clearer.....so now can i....safetly say that on the ikon i can keep......

1) city driving - 28 psi on all 4 tyres

2) long distance / xpressway travel - 30 psi on all 4 tyres ( 2 people )
- 32 psi on all 4 tyres ( 4-5 people with luggage )

right ??
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Old 6th April 2005, 12:48   #57
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i put 30 front 32 rear and stepney all the time i my ikon 1.6
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Old 6th April 2005, 12:50   #58
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okay ...thats made things a lot clearer.....so now can i....safetly say that on the ikon i can keep......

1) city driving - 28 psi on all 4 tyres

2) long distance / xpressway travel - 30 psi on all 4 tyres ( 2 people )
- 32 psi on all 4 tyres ( 4-5 people with luggage )

right ??
Yeah something like that. But, try not to go below the recomended pressure.

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Old 6th April 2005, 12:52   #59
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i put 30 front 32 rear and stepney all the time i my ikon 1.6
I'm in the habit of keeping 30-31 at the front and 29 at the rear.

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Old 6th April 2005, 12:52   #60
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Source : http://www.simextyre.com/Tyre_Tips.asp

An excellent resource for tyre pressures at various loads and speeds. I believe, it is for Australia, where conditions will be similar to India (hot climate).
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