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Old 18th June 2018, 20:27   #61
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Default Re: Changes in tire pressure - highway driving

I used to stick with 30-32 PSI for several years, until I stepped up the game (aka tyre pressure)

I went all the way to 36PSI for my 185 70 R14 and the result is


-better mileage
-no scraping or bottoming out at all either in city or highways
-no wobbling or bumpy rides
-AND MOREOVER...NO PUNCTURES, earlier I used to have them once every 6 months
-did OOTY and WAYANAD trips from Bangalore, and totally satisfied with fuel economy and ride.
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Old 18th June 2018, 21:26   #62
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Default Re: Changes in tire pressure - highway driving

The whole discussion on tyre pressure being 2-4 psi up or down holds any value if you have a well calibrated gauge at hand.
Many folks here stating about so and so pressure and its effects - I wonder how many have their own gauges. A large number of general population would be depending on bunk gauges or roadside tyre shop gauges and most of them are far from accurate. I have started to use a high quality electronic gauge recently and am astonished to find that some of these local shops fill up to 45-47 psi when asked for 30-32.
An untrained eye cannot make any difference by looking at the tyre itself.

So, if one is serious about tyre pressure then buying a good gauge is the first step one should take.
Cheers!!
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Old 18th June 2018, 22:32   #63
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Default Re: Changes in tire pressure - highway driving

Quote:
Originally Posted by kishgator View Post
I used to stick with 30-32 PSI for several years, until I stepped up the game (aka tyre pressure)

I went all the way to 36PSI for my 185 70 R14 and the result is
You will damage your bearing, if you drive with tyres inflated above the recommended pressure.
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Old 18th June 2018, 23:17   #64
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Quote:
Originally Posted by aspire View Post
You will damage your bearing, if you drive with tyres inflated above the recommended pressure.

Really? That is new to me, why would that be?

Jeroen
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Old 31st December 2018, 14:27   #65
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Default Re: Changes in tire pressure - highway driving

I always use Nitrogen in all my tires. Recently, due to punctures, I had air in the front and Nitrogen at the rear tires.

When i entered the car in the morning, the front tires showed 31/32 PSI, while the rears were at 34/35. It being December, the tires must have cooled down overnight.

After driving for around 20 KM's to office in Mumbai's traffic, the tyre pressures read 37 for the front and 36 for the rear.

Changes in tire pressure - highway driving-mvimg_20181221_100536_exported_3959569571425936746.jpg

The front had gone up by 5/6 PSI while the rear expanded by only 1/2 PSI.

I always questioned myself, as to why I fill Nitrogen in my car. Not anymore!!

Last edited by suku_patel_22 : 31st December 2018 at 14:30.
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Old 1st January 2019, 19:53   #66
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Default Re: Changes in tire pressure - highway driving

^^^ This last post has created some doubts in my mind.

The manufacturer recommends an ideal air pressure which is supposed to be maintained when the tyre is cold. So when the car starts rolling, the manufacturer expects the pressure to go up as the tyre heats up. Typically I have observed 30 psi cold becomes about 32 to 33 psi when you drive at normal speeds in the city. The same 30 psi becomes about 35 to 37psi when you drive at 100+ speeds on the highway. It means that the manufacturer has factored these increases when he has given his recommendations. 35 psi on the highway will make the tyre less prone to flexing and less heat build up for the rubber + better handling.

Obviously the manufacturer has given the recommendation for air and not nitrogen since 99% of people fill air and filling nitrogen is not really a standard practice in the automotive world.

So let us take the example of two cars :

Car A
  • Owner fills air 30 psi when cold
  • In the city his car is running on 33 psi
  • On the highway his car is running on 35 psi

Car B
  • Owner fills nitrogen 30 psi when cold
  • In the city his car is running on 31 psi
  • On the highway the car is running on max 32 psi
Now as per manufacturer recommendation, the car should be running on 35 psi on the highway whereas Car B is running on 32 psi, which means it is underinflated by 3 psi. Wouldn't this cause the rubber to flex a bit more and cause heat build up in the rubber, not to mention floaty handling?

So my surmise is that people who are particular about fillng nitorgen, must really overinflate by atleast 5 to 6 psi before venturing out on the highway. And then deflate it by 3 psi when in the city, to not suffer an overly hard ride. In other words why bother with nitrogen, when regular air does it automatically for you?
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Old 1st January 2019, 20:44   #67
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Default Re: Changes in tire pressure - highway driving

A little OT, suppose I inflate tyres (normal air) after a long drive in the urban environment (when tanking up) say to 35 psi instead of the 32 psi which I normally do, is it wrong or would you recommend it. Agreed it's better not to inflate after a long drive.
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Old 1st January 2019, 20:52   #68
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Default Re: Changes in tire pressure - highway driving

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Originally Posted by Durango Dude View Post
A little OT, suppose I inflate tyres (normal air) after a long drive in the urban environment (when tanking up) say to 35 psi instead of the 32 psi which I normally do, is it wrong or would you recommend it. Agreed it's better not to inflate after a long drive.
If you do this, when you check the pressures at cold temperature (as recommended), the pressures would be 33 or 34psi may be. If you fill 32psi when hot, it would be 30-31psi when cold.

I generally fill up air when the tyres are cold. My regular filling station is just 500 meters from home so the drive to that bunk is gentle anyway. Recommended pressure for my car (Creta) is 33 psi so I fill up the same. I have TPMS installed - keep checking every day, hence air top-up is done only when air pressure reads 32psi on the TPMS.

Last edited by GTO : 2nd January 2019 at 07:27. Reason: Correcting last line
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Old 1st January 2019, 21:57   #69
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Default Re: Changes in tire pressure - highway driving

Quote:
Originally Posted by Durango Dude View Post
A little OT, suppose I inflate tyres (normal air) after a long drive in the urban environment (when tanking up) say to 35 psi instead of the 32 psi which I normally do, is it wrong or would you recommend it. Agreed it's better not to inflate after a long drive.
I really feel a difference between nitrogen and normal air, specially in air retention.. I fill air after 28-30 days, i.e 4 weeks and it loses about 1 psi or sometimes 2, that's it. I'd prefer to keep the psi to permanently 31 or so as that strikes the perfect comfort balance but I succumb to keep it at around the recommended 33 so that my checking interval can be long.

You can set about 1-2 psi higher than recommended under hot tyre conditions.. though I feel that there is no thumb rule as such, in my previous car ownerships as a teen (before being bombarded by car knowledge) I'd check air once in 2-3 months (low running though), I'd push alignment/balancing to double its recommended intervals and yet the car tyres were quite fine at the end of the day. Since yours is low running as well I'd say you won't make much of a mistake with tyres. The best care for tyres is gradual acceleration and trying to avoid rubber smashing potholes.
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Old 1st January 2019, 22:51   #70
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We are talking a few psi here. Your biggest challenge, I think, is to find a reliable accurate, manometer. How do you know it is accurate?

All manometer become less reliable over time. So you need to get them calibrated once a year, or buy a new calibrated one. The manometer at petrol stations are extremely unreliable. Not just in India, but anywhere in the world. They never ever get replaced or recalibrated. As long as they provide a reading, they are considered to be good enough.

I have my own compressor and manometer. Only recently I found out it was showing way to low a pressure. The trick is to find somebody or somewhere with a reliable, calibrated manometer. MOT stations in Europe are a good source as they do get checked on a regular basis.

But any discussion on tire pressure without having evidence you are having reliable accurate measures is a bit academic.

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Old 2nd January 2019, 07:56   #71
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Default Re: Changes in tire pressure - highway driving

Quote:
Originally Posted by a4anurag View Post
If you do this, when you check the pressures at cold temperature (as recommended), the pressures would be 33 or 34psi may be. If you fill 32psi when hot, it would be 30-31psi when cold.

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Quote:
Originally Posted by dark.knight View Post

You can set about 1-2 psi higher than recommended under hot tyre conditions.. though I feel that there is no thumb rule as such, in my previous car ownerships as a teen (before being bombarded by car knowledge) I'd check air once in 2-3 months (low running though), I'd push alignment/balancing to double its recommended intervals and yet the car tyres were quite fine at the end of the day. Since yours is low running as well I'd say you won't make much of a mistake with tyres. The best care for tyres is gradual acceleration and trying to avoid rubber smashing potholes.
Last night had a drive till OMR and found the ride rather 'hard' given the Honda City already had a firm ride. But I'll leave it there and wait for the tyre to deflate with time as my running is rather low. I think the best would be to check tyre pressure once in every two months for the Honda City to ride supple.
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Old 2nd January 2019, 22:53   #72
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Default Re: Changes in tire pressure - highway driving

I inflate my tyres once a month at a HP Petrol station practically next door, so my tyres will be cool. I go alone, and get down from the car while checking pressure.

It is a decent enough place, they have separate pumps for air and N2. I am not sure it is N2 though the board says so, but the machine and gauge are a lot better and appear more expensive than the simple air pump, and there is less crowd because they charge Rs.5 per wheel. I feel that gauge will be the more accurate among the two, and I don't mind the charge because I never fill petrol there! So it is always the N2 pump!

My recommended pressure is 30 PSI but I keep 34 because I check only once a month as my car is parked throughout the week, and is used only during weekends. It works fine for me, the pressure usually goes down to 33 or 32 when I check the next time. I keep the same pressure whether I go on the highway or drive inside the city.

Last edited by Gansan : 2nd January 2019 at 22:55.
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Old 3rd January 2019, 15:09   #73
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Default Re: Changes in tire pressure - highway driving

Unless one own good gauge it’s very difficult to guarantee correct tyre pressure. To have consistent tire pressure, I bought Air compressor and Tire Pressure Gauge. I made a practice to check tire pressure very week, and before start of highway ride. Over these years following are my observations,

• Gauge on air compressor is not reliable no matter how good it is, once compressor get heated, its start showing higher psi.
• Rarely had drop in tire pressure, unless there was puncture. In fact my Yokohama tires hold same pressure for months!
• Checking tire pressure every week means, would catch any puncture early! Thus, fixing same will help indirectly in tire health.
• Having higher pressure helps in highway drive fuel economy. So, I stick to Ford recommended pressure on full load for highway journey (36 psi front, 41 psi back).
• Even for city ride adding additional 4 to 5 psi helps. In 9 years I am on second set of tires (first one replaced after 42K km).
• Doing tire rotation in fixed interval greatly helps in tyre aging along with other benefit it brings. So, I stick 3 months, alignment and tire rotation.
• None of the fuel pump, or N2 machine are accurate! Once tire cool down next morning, tire pressure of each tire shows different values.
• Service center do not have good gauge! I find every time car came back from service, all tires having different pressure. So make a habit of checking the tire pressure next morning.
• Riding sanely makes maximum difference in tire wear.
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Old 4th January 2019, 14:38   #74
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Default Re: Changes in tire pressure - highway driving

Quote:
Originally Posted by suku_patel_22 View Post
When i entered the car in the morning, the front tires showed 31/32 PSI, while the rears were at 34/35. It being December, the tires must have cooled down overnight.
...
After driving for around 20 KM's to office in Mumbai's traffic, the tyre pressures read 37 for the front and 36 for the rear.
...
I always questioned myself, as to why I fill Nitrogen in my car. Not anymore!!
Illogical reasoning, I'm afraid.

For a front-wheel-drive vehicle, the front tyres will always take more stress - driving, braking as well as steering. So they would be expected to build up heat more than the rear tyres. So long as the increase in pressure after an extended drive is not more than 4-5 psi, it is safe to assume the tyres are correctly inflated. If the pressure buildup is greater, the tyres were running underinflated to begin with.

Would be unusual for a FWD to run lower front tyre pressures than the rear tyres. What is the manufacturer-recommended tyre pressure for your car?

Edit:
Rule of thumb: Always expect a 4 psi increase in tyre pressure for correctly inflated tyres on extended city or highway drives, for correctly inflated tyres. Rule not applicable for track use / racing. A higher pressure buildup (7-8 psi or even more) indicates the tyre started off underinflated from cold. Overinflated tyres can also show increase of pressure, but not exceeding 4 psi.

Oh, BTW, everybody uses nitrogen in their cars - it's only slightly adulterated! About 22% adulterated.
What makes a difference is the water vapour (moisture) in the air we fill in the tyres. Dry nitrogen filled from a tank makes sense. The nitrogen generators that pumps use are delivering neither pure nitrogen (the max they can concentrate is 92-93% N2), nor is it moisture-free.

Last edited by SS-Traveller : 4th January 2019 at 14:50.
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Old 4th January 2019, 14:58   #75
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Default Re: Changes in tire pressure - highway driving

Quote:
Originally Posted by Jeroen View Post
All manometer become less reliable over time. So you need to get them calibrated once a year, or buy a new calibrated one.
How do we calibrate or what's your method for re-calibration?
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