Correct Airpressure For Tires?

[EnSvenskTiger]

Correct air pressure for tires?

I recently bought a new Isuzu D-max and after driving it for 130 km I decided to check the pressure, the attendant at the fuel station hooked the tire up to a digital device and I ordered 29 PSI as recommended in the manual. POF! The meter went up to 44 PSI! Checking the other tires same result. I didn't dare to make any adjustment as his device might be malfunctioning, so of we go to Isuzu garage, “check lom kap!”, and they adjusted the pressure to 29 PSI( Why do they use PSI?). Yesterday I checked on the internet and the MAXIMUM pressure for the Bridgestone Dueler H/T 689 is 44 PSI. Why was the car delivered with this pressure? Is it better for fuel economy to increase the pressure?

I can say that I feel any difference now but I'm no expert and drives very slowly.

Experts?

Regards

Tiger

[Kwasaki]

My top Thai mechanic says 80 psi is good because you don't have to bother for about a year before checking it again.

[Pomthai]

That 29 PSI you had it adjusted too is correct, except its the cold setting. You will find that since you drove there to have it adjusted the tyres will be a little low on pressure overall if set at 29 PSI while warm. I have a DMAX and run it at 31 PSI all round from cold. On the occasions when I've checked or tested the pressures when the tyres are warm, the usual reading is about 38 PSI, it looks like I gain about 7 PSI due to heat and air expansion from driving.

You make you own decision but if I wanted them at 29 like the door insert says, I'd set them to 29 cold at home or 35-36 at the gas station.

What ever you decide, if you set them to 29 PSI warm then you will be quite likely be causing unnecessary wear and increasing your fuel consumption.

Edited October 31, 2010 by Pomthai

[Kwasaki]

My top Thai mechanic says 80 psi is good because you don't have to bother for about a year before checking it again.

oooooooh, you are awful, but l like you.

( for old Brits only )

Dick Emery, yes !!! l think he would of love it here in Thailand.

If you didn't laugh you would cry for sure, or look for the nearest bridge as they say.

[MoonRiverOasis]

The reason why overfilling tires is so commonplace is actually a little innocent..

The PSI/kPa rating embossed on Bicycle tires is the recommended inflation pressure, while the numbers on car/truck tires are the maximum inflation pressure. The average Thai just doesn't know enough English to understand the difference.

In answer to the OP's question, your dealership has it right, and the gas station attendant just doesn't know any better...

[katabeachbum]

The reason why overfilling tires is so commonplace is actually a little innocent..

The PSI/kPa rating embossed on Bicycle tires is the recommended inflation pressure, while the numbers on car/truck tires are the maximum inflation pressure. The average Thai just doesn't know enough English to understand the difference.

In answer to the OP's question, your dealership has it right, and the gas station attendant just doesn't know any better...

just came back from a 4.070km roadtrip. Had 20k km service on my 2010 Vigo done in Nong Kai, and it came out with 40 psi tyre pressure.

Recommended tyre pressure from Toyota is 29psi as indicated on sticker in doorsill, but its not the first Toyota/Honda service my tyres have been overinflated.

I always have a 200 baht Tesco pressure gauge in my truck, since the ones in gas stations are often not correct, and it allows me to check pressure with cold tyres late night or early morning.

[EnSvenskTiger]

Thanks all!

80 PSI? Hrrmmm!

Well,Tesco here I come with 200 B in my hand. 35 PSI is probably a good figure to aim at.

Regards from a rainy Trang

Tiger

[mdechgan]

My old, old previous Dmax 1st generation cab had different tire pressures for front and back. I think it was 29 front and something like 44 or 54 for the rear.

My current 4x4 has 29 recommended for all four.

My Navara cab has 35 recommened for all four.

I think most people overinflate their tires because it drives better, better mileage and acceleration because of less resistance or just because they are lazy to check every month like the dealers do.

[katabeachbum]

My old, old previous Dmax 1st generation cab had different tire pressures for front and back. I think it was 29 front and something like 44 or 54 for the rear.

My current 4x4 has 29 recommended for all four.

My Navara cab has 35 recommened for all four.

I think most people overinflate their tires because it drives better, better mileage and acceleration because of less resistance or just because they are lazy to check every month like the dealers do.

overinflated tyres increases braking distance and reduces traction. a lot.

car manufactorers spend millions of km and years to test cars before selling them. including tyre pressure. goal is max lifetime, traction and minimum braking distance, which recommended pressure provides

[Deeral]

It seems to norm in Thailand to drastically over-inflate tyres - I can't find any sound reason for this - only folk-lore.

THe correct pressures for standard tyres are usually posted on the indie of the R/H front door.

you will fuc_k-up tyre wear, handling and all sorts of stuff by over-inflating and I can't find a single good reason for doing it.

[Deeral]

The reason why overfilling tires is so commonplace is actually a little innocent..

The PSI/kPa rating embossed on Bicycle tires is the recommended inflation pressure, while the numbers on car/truck tires are the maximum inflation pressure. The average Thai just doesn't know enough English to understand the difference.

In answer to the OP's question, your dealership has it right, and the gas station attendant just doesn't know any better...

just seen this - but I checked with my tyre shop on this and they didn't agree - when I then asked why they just shrugged!

[katabeachbum]

It seems to norm in Thailand to drastically over-inflate tyres - I can't find any sound reason for this - only folk-lore.

THe correct pressures for standard tyres are usually posted on the indie of the R/H front door.

you will fuc_k-up tyre wear, handling and all sorts of stuff by over-inflating and I can't find a single good reason for doing it.

at least 3 reasons for doing it, but none of them good

less fuel consumption

lighter steering

increased load capasity, IOW if tyres to low load index for load, at least max load index is achieved with TYRES recommended max pressure

[MoonRiverOasis]

The reason why overfilling tires is so commonplace is actually a little innocent..

The PSI/kPa rating embossed on Bicycle tires is the recommended inflation pressure, while the numbers on car/truck tires are the maximum inflation pressure. The average Thai just doesn't know enough English to understand the difference.

In answer to the OP's question, your dealership has it right, and the gas station attendant just doesn't know any better...

just seen this - but I checked with my tyre shop on this and they didn't agree - when I then asked why they just shrugged!

Oh well, if your tire shop shrugs their shoulders at the question, I must be obviously wrong

I sit corrected

[Deeral]

It seems to norm in Thailand to drastically over-inflate tyres - I can't find any sound reason for this - only folk-lore.

THe correct pressures for standard tyres are usually posted on the indie of the R/H front door.

you will fuc_k-up tyre wear, handling and all sorts of stuff by over-inflating and I can't find a single good reason for doing it.

at least 3 reasons for doing it, but none of them good

less fuel consumption

lighter steering

increased load capacity, IOW if tyres to low load index for load, at least max load index is achieved with TYRES recommended max pressure

Effects of drastic overinflation or any overinflation will make such a tiny difference on fuel consumption - if any you won't notice it.

Lighter steering is also unlikely except if your tyres were UNDER-inflated before. It will of course cause unusual wear on the centre of the tread.

Inflating your tries more doesn't increase load capacity, a certain amount of inflation makes the vehicle handle better when loaded (caravan owners take note!!). but significantly OVER inflating them will make the tyre more likely to give way - you may have noticed the large amount of overloaded pickups by the side of the road - many have simply burst a tire.

Moon River - as ever, what ARE you on about?

[Deeral]

BTW - MR, if you told me the time I'd get a second opinion (pardon the pun)

[katabeachbum]

It seems to norm in Thailand to drastically over-inflate tyres - I can't find any sound reason for this - only folk-lore.

THe correct pressures for standard tyres are usually posted on the indie of the R/H front door.

you will fuc_k-up tyre wear, handling and all sorts of stuff by over-inflating and I can't find a single good reason for doing it.

at least 3 reasons for doing it, but none of them good

less fuel consumption

lighter steering

increased load capacity, IOW if tyres to low load index for load, at least max load index is achieved with TYRES recommended max pressure

Effects of drastic overinflation or any overinflation will make such a tiny difference on fuel consumption - if any you won't notice it.

Lighter steering is also unlikely except if your tyres were UNDER-inflated before. It will of course cause unusual wear on the centre of the tread.

Inflating your tries more doesn't increase load capacity, a certain amount of inflation makes the vehicle handle better when loaded (caravan owners take note!!). but significantly OVER inflating them will make the tyre more likely to give way - you may have noticed the large amount of overloaded pickups by the side of the road - many have simply burst a tire.

Moon River - as ever, what ARE you on about?

a TYRES max load capacity is obtained at max airpessure for this TYRE as indicated on sidewall of tyre. This aipressure is usually 30-40% higher than VEHICLES recommended tyre pressure

as you say overinflating makes wear in center of tyre, thus lighter steering due to less tyre surface contact/pressure/frction with road.

same reason for reduced fuel consumption, similar effect to installing smaller tyres width like most hybrids do to improve milage

a few hundred k km testdriving also tought us under- or overinflating 20% provides 5% change in fuel consumption

Edited November 4, 2010 by katabeachbum

[tellaziz]

It seems to norm in Thailand to drastically over-inflate tyres - I can't find any sound reason for this - only folk-lore.

THe correct pressures for standard tyres are usually posted on the indie of the R/H front door.

you will fuc_k-up tyre wear, handling and all sorts of stuff by over-inflating and I can't find a single good reason for doing it.

at least 3 reasons for doing it, but none of them good

less fuel consumption

lighter steering

increased load capacity, IOW if tyres to low load index for load, at least max load index is achieved with TYRES recommended max pressure

Effects of drastic overinflation or any overinflation will make such a tiny difference on fuel consumption - if any you won't notice it.

Lighter steering is also unlikely except if your tyres were UNDER-inflated before. It will of course cause unusual wear on the centre of the tread.

Inflating your tries more doesn't increase load capacity, a certain amount of inflation makes the vehicle handle better when loaded (caravan owners take note!!). but significantly OVER inflating them will make the tyre more likely to give way - you may have noticed the large amount of overloaded pickups by the side of the road - many have simply burst a tire.

Moon River - as ever, what ARE you on about?

a TYRES max load capacity is obtained at max airpessure for this TYRE as indicated on sidewall of tyre. This aipressure is usually 30-40% higher than VEHICLES recommended tyre pressure

as you say overinflating makes wear in center of tyre, thus lighter steering due to less tyre surface contact/pressure/frction with road.

same reason for reduced fuel consumption, similar effect to installing smaller tyres width like most hybrids do to improve milage

a few hundred k km testdriving also tought us under- or overinflating 20% provides 5% change in fuel consumption

A tires load index is consistant throughout the range of inflation pressures it may be subjected to up to the maximum pressure rating of the tyre.It does not increase with pressure. The vehicle manufacturer advises the tire pressure range versus load as a recommendation. This is because they designed the vehicle.

Significant deviation from the manufacturers recommendations can seriously compromise the safety of the vehicle in terms of manoeverability and braking in circumstances unforseen by individuals who attempt changes on a trial and terror basis. If you're ever in doubt, staying within the manufacturers recommendations is always safest.

Buy a tire gauge and check tire pressures on a regular basis (say every week) especially if the inflation has been carried out by a third party (of any nationality).

[Kwasaki]

Put Nitro gas in doesn't lose anything, Oh !!! Noooo !! What did l just type, must put that notice back up, do post anything after 6 beer changs, slap, slap to myself.

[Deeral]

Katabeachbum - well wide of the mark .........check your science

as fo nitrogen, well that has already been discussed and dismissed on another thread.......not what the papers say.

Edited November 5, 2010 by Deeral

[katabeachbum]

Katabeachbum - well wide of the mark .........check your science

oh deer, we all know you have no clue :lol:

my facts is from my previous employer, an upmarket european car maker. millions of km testdriving, years of wear and tear and crashes

[hakku]

katabb is correct in everything he writes down. Load capacity of the tyre increases with more inflation. of course the loadindex of a tyre stays the same because it is just a maximum number at a certain pressure (35 psi for standard tyres, and 41 psi for XL). The load capacity is proportional to the pressure. Full stop.

Thais love to overinflate mainly cos they think it saves fuel.

H

Edited November 5, 2010 by hakku

[Kwasaki]

Here again what the bloody heck is BTW... Mr. mean ?????

And Deeral after the third bleep, it will be 20.27 precisely. :jerk:

P.S means post script... Nitro in tyres in Thailand is great l don't care a monkeys dangling things what anybody says the proof of the pudding is in the eating. full stop as somebody said.

Edited November 5, 2010 by Kwasaki

[Deeral]

Sorry mate but I'm afraid your science leaves a lot to me desired. Pity none of that work resulted in a bit of basics rubbing off on you.That's why I thought you were a mechanic - very little understanding of engineering.

[Deeral]

Sorry mate but I'm afraid your science leaves a lot to me desired. Pity none of that work resulted in a bit of basics rubbing off on you.That's why I thought you were a mechanic - very little understanding of engineering.

As ever the motoring threads are full of "don't knows" !

BTW and PS - Air can't make a tyre stronger

Edited November 5, 2010 by Deeral

[tellaziz]

katabb is correct in everything he writes down. Load capacity of the tyre increases with more inflation. of course the loadindex of a tyre stays the same because it is just a maximum number at a certain pressure (35 psi for standard tyres, and 41 psi for XL). The load capacity is proportional to the pressure. Full stop.

Thais love to overinflate mainly cos they think it saves fuel.

H

Every vehicle manufacturer selects, tests, and approves various tires for each model, according to weight performance, size, and other criteria. Load and speed indexes are very important in tire selection and determine the appropriate air pressure

The load index is marked on the sidewall of a tire as an alphanumeric combination, consisting of two parts. This is referred to as the 'Service Description'. For example, for characters '100T', '100' would be the load index, which represents the load carrying capacity and 'T' would be the speed rating.

The load index is a numerical code that corresponds to the maximum weight a tire can support. A tire's load multiplied by 2 must cover the gross single axle load of your vehicle. A load index of 100 will support 800kg and no more. It doesn't matter how much air you put in the tire.

In answer to the OP's question:-

There are two recommended tire pressures for your vehicle: one for travel at maximal vehicle capacity weight or on the highway and one for travel at normal vehicle capacity weight. Tire pressure should be checked when the tires are cold. In other words, if your vehicle has been parked for at least two hours and has not been driven more than 1-3 miles since, you will get an accurate tire pressure reading. If, on the other hand, you stop at a highway rest area and your tires are not cold, add 0.3 bar to the recommended pressure (1 bar is 15psi near as dammit). Be sure to check the pressure again once the tires are cold. Never lower pressure if tires are not cold

If you doubt me, look at a website from a quality tire manufacturer. Say Dunlop or Michelin. Or, better still, just contact Isuzu customer service/technical department. All this will just confirm what is in the handbook.

I'm so, happy I've never had to drive a European car.

[hakku]

H

Every vehicle manufacturer selects, tests, and approves various tires for each model, according to weight performance, size, and other criteria. Load and speed indexes are very important in tire selection and determine the appropriate air pressure

The load index is marked on the sidewall of a tire as an alphanumeric combination, consisting of two parts. This is referred to as the 'Service Description'. For example, for characters '100T', '100' would be the load index, which represents the load carrying capacity and 'T' would be the speed rating.

It doesn't matter how much air you put in the tire.

You are almost correct!Here's how your last paragraph should read:

The load index is a numerical code that corresponds to the maximum weight a tire can support AT A STANDARD PRESSURE (35psi for standard tires and 41PSI for extra load tires). A tire's load multiplied by 2 must cover the gross single axle load of your vehicle. A load index of 100 will support 800kg and no more. AT A PRESSURE OF 35PSI

I don't really care if you agree or not, but thats how it is. Attached a Good year PDF as illustration of different load capacities at different pressures. But then again, what do i know about tires?

Hak

rv_inflation.pdf

[katabeachbum]

Every vehicle manufacturer selects, tests, and approves various tires for each model, according to weight performance, size, and other criteria. Load and speed indexes are very important in tire selection and determine the appropriate air pressure

The load index is marked on the sidewall of a tire as an alphanumeric combination, consisting of two parts. This is referred to as the 'Service Description'. For example, for characters '100T', '100' would be the load index, which represents the load carrying capacity and 'T' would be the speed rating.

It doesn't matter how much air you put in the tire.

You are almost correct!Here's how your last paragraph should read:

The load index is a numerical code that corresponds to the maximum weight a tire can support AT A STANDARD PRESSURE (35psi for standard tires and 41PSI for extra load tires). A tire's load multiplied by 2 must cover the gross single axle load of your vehicle. A load index of 100 will support 800kg and no more. AT A PRESSURE OF 35PSI

I don't really care if you agree or not, but thats how it is. Attached a Good year PDF as illustration of different load capacities at different pressures. But then again, what do i know about tires?

Hak

so true

and a 100 load index tyre with 20 psi is unable to carry more than 5-600kg, and will blow up after 10-30 minutes loaded with 800kg at 80kmh. air does make the tyre strong to much air increases brakingdistance and reduces traction though

as for the poster stating 2 recommended airpessures for OPs pickup, not correct. The high load index oversized tyres on top of the line LOS pickups works well with one tyre pressure all conditions. However I prefere to increase pressure with 10% on a long trip heavy loaded (700kg) and speeds 140-160kmh all day

[Kwasaki]

Here again what the bloody heck is BTW... Mr. mean ?????

And Deeral after the third bleep, it will be 20.27 precisely. :jerk:

P.S means post script... Nitro in tyres in Thailand is great l don't care a monkeys dangling things what anybody says the proof of the pudding is in the eating. full stop as somebody said.

I ignore BTW cos l don't know what it means either, but perhaps it makes you look cool eh.

Well know l am cooler than "drearyal" doesn't make any sense, we have got PS now !!! is that HP or PSI or BTW or ABS.:jerk:

[Kwasaki]

Here again what the bloody heck is BTW... Mr. mean ?????

And Deeral after the third bleep, it will be 20.27 precisely. :jerk:

P.S means post script... Nitro in tyres in Thailand is great l don't care a monkeys dangling things what anybody says the proof of the pudding is in the eating. full stop as somebody said.

I ignore BTW cos l don't know what it means either, but perhaps it makes you look cool eh.

Well know l am cooler than "drearyal" doesn't make any sense, we have got PS now !!! is that HP or PSI or BTW or ABS.:jerk:

I know what B O L L O C K S is the abbreviation for, and T W A T for instance. Is there a listing of ' know it all ' abbreviations for us common folk to turn too.

l know the latter " That Waiting Ambulance There "