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Old 14th December 2010, 16:44   #121
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Default Re: The right tyre pressure?

The recommended tyre pressure for the Gypsy is 20psi front and 26psi for rear. I drive 3km to the shell outlet so on a mere hunch, considering it is not cold pressure decided to use 24 front and 30 rear. I just loved the handling at these pressures initially on that day - It gave me so much confidence I did my first attempts at highway overtaking (its my new car) above 80+ speeds confidently on curves and cornered S-Bends on Kanakpura Road with elan. The vehicle just hugged the road like a magnet at high speeds and sharp corners, earlier there was a unsteady drift to the handling. Now I cant "feel" the improvement, but have decided to stick to it in the long term. The steering was more steady than at 32psi that the Yoko dealer put when I purchased them. I use Geolander A/T-S 215/75/R15.

HTH

Last edited by Ragul : 14th December 2010 at 16:47.
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Old 14th December 2010, 16:52   #122
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Default Re: The right tyre pressure?

My friend has this Volkswagen Jetta 2010 model with the stock 16" alloy wheels. The manual says to maintain the tyre pressure of 32 PSI for two people and 40 PSI when driving with 5 people. The dealer is unable to explain this. Any reason for this wide difference in tyre pressure?
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Old 14th December 2010, 17:33   #123
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Default Re: The right tyre pressure?

Could anyone please let me know what should be the actual tyre pressure for Maruti SX4 Zxi? (205/60 R16)

Some people say 32PSI, 30 for all tyres, 30 for front and 32 for back.

I am utterly confused.

Please help.
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Old 15th December 2010, 14:02   #124
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Default Re: The right tyre pressure?

Quote:
Originally Posted by Digital Vampire View Post
my TPMS (can read temperature and pressure accurate to 2 decimal places while running) that Nitrogen filled tyres warm up the same way as Normal Air filled tyres and they also exhibit pressure variations with temperature.
You are the best equipped to tell us how do normal air filled tyres heat up after being run. You could do short city run and a longish highway and let us know graphically. I mean a time/distance vs temperature graph
Thanks
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Old 15th December 2010, 14:08   #125
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Default Re: The right tyre pressure?

When I got my alloys fixed.. I had the new tubeless tires filled with Nitrogen.. now can I go to a regular air pump in a petrol bunk and fill/adjust the tyre pressure? Or should I ONLY go to a place where I can get it filled with nitrogen only again? Please advice.
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Old 15th December 2010, 15:19   #126
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Default Re: The right tyre pressure?

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Originally Posted by goandude View Post
You are the best equipped to tell us how do normal air filled tyres heat up after being run. You could do short city run and a longish highway and let us know graphically. I mean a time/distance vs temperature graph
Thanks

Quoting from memory: Testing on Normal Air vs Nitrogen (posted elsewhere here)

Temperature:

Both normal air as well as nitrogen increased the tyre temperature by 4-5 degrees over a 10KM home-office run (average speed was less than 30 kmph)

Over a 400KM+ run, I observed similar effects but the temperature rise was 8-12 degrees but consistent between them over varied terrain/climates. Average speed was below 90Kmph with occasional blips of 160kmph.

Pressure:
Both normal air as well as nitrogen increased the tyre pressure by 1.5-2.5 PSI over a 10KM run.

Over a 400KM+ run, I observed similar effects on both nitrogen filled tyre vs Normal Air filled tyres and the pressure rise was consistent between them averaging over 3-6 PSI over varied terrain/climates.

Side Note: No four tyres would be at the exact same temperature or pressure due to variation in the friction they go through. The variation of temperature is not much during early morning (parked car) but still the tyre nearer to the Open slit/Window will show ~1 deg less than others due to better cooling.

All my cars are running normal air now and I don't plan to waste money on Nitrogen anymore. If anyone in Bangalore want to personally test and experience the results first hand, feel free to PM me and I can arrange for a more detailed data-logging if there is sufficient interest so that we can bury this stupid Nitrogen Urban Legend forever.

Last edited by Digital Vampire : 15th December 2010 at 15:36.
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Old 15th December 2010, 15:50   #127
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Default Re: The right tyre pressure?

Quote:
Originally Posted by bkbkr1212 View Post
Could anyone please let me know what should be the actual tyre pressure for Maruti SX4 Zxi? (205/60 R16)

Some people say 32PSI, 30 for all tyres, 30 for front and 32 for back.

I am utterly confused.

Please help.
Open your driver's side door and look at the plate fixed to the body near the bottom. It mentions the tyre pressure. The recommended pressure for ZXI is 30 PSI for all the tyres. However the manual recommends to increase the pressure by 5 PSI in case you are going for a long drive on highways. I normally keep 32 PSI and am comfortable with it.

Murthy
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Old 15th December 2010, 16:35   #128
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Default Re: The right tyre pressure?

Quote:
Originally Posted by Digital Vampire View Post
Quoting from memory: Testing on Normal Air vs Nitrogen (posted elsewhere here)

Temperature:

Both normal air as well as nitrogen increased the tyre temperature by 4-5 degrees over a 10KM home-office run (average speed was less than 30 kmph)

Over a 400KM+ run, I observed similar effects but the temperature rise was 8-12 degrees but consistent between them over varied terrain/climates. Average speed was below 90Kmph with occasional blips of 160kmph.

Pressure:
Both normal air as well as nitrogen increased the tyre pressure by 1.5-2.5 PSI over a 10KM run.

Over a 400KM+ run, I observed similar effects on both nitrogen filled tyre vs Normal Air filled tyres and the pressure rise was consistent between them averaging over 3-6 PSI over varied terrain/climates.

Side Note: No four tyres would be at the exact same temperature or pressure due to variation in the friction they go through. The variation of temperature is not much during early morning (parked car) but still the tyre nearer to the Open slit/Window will show ~1 deg less than others due to better cooling.
Thanks DV for the very informative post. This is the type of information that makes Team bhp such a great forum for us enthusiasts.

My manual says to inflate cold pressure higher for fast drives. but if the temp already increases with running where is the need to increase cold pressures.
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Old 15th December 2010, 21:27   #129
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Originally Posted by gavinimurthy View Post
I normally keep 32 PSI and am comfortable with it.
Me too! I keep 32 PSI for all four tyres of my Alto and check pressure once every two weeks. I keep 35 PSI for the spare tyre and check it once a month.

I will drive the car alone (~ 2 KM) at 8.00 AM on a Sunday to my favourite Shell pump for this, and get down from the car while the air is being checked. I believe passenges should not be sitting inside while checking tyre pressure.

I also keep 4 PSI more than the recommended pressure for my bike.
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Old 17th December 2013, 21:12   #130
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Default Re: The right tyre pressure?

Hi Experts,
I am planning a long highway drive from Mumbai to Udaipur.
I thought of checking what should be the correct tyre pressure for my car?
Dzire Lxi CNG fitted - which means an extra 75kgs in the boot!
Also, note that the car will be fully loaded with all 5 passengers and the boot will be fully loaded with luggage.

Please help!
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Old 18th December 2013, 09:30   #131
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^^ With a CNG kit and a full complement of passengers + luggage, it would be prudent to stick to the Maruti recommended tyre pressure.
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Old 18th December 2013, 10:55   #132
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Default Re: The right tyre pressure?

Quote:
Originally Posted by goandude View Post
Thanks DV for the very informative post. This is the type of information that makes Team bhp such a great forum for us enthusiasts.

My manual says to inflate cold pressure higher for fast drives. but if the temp already increases with running where is the need to increase cold pressures.
At higher speeds tyres get very less time to spring back from compression at the point of contact. Higher pressure is recommended to counter higher temprature build up.
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Old 27th January 2014, 19:53   #133
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So for my last trip to rajasthan, I followed the advice given on tbhp.
Also I double checked the recommended pressure in the manual. It said 5psi more than normal. i.e. 33 + 5= = 38

I did that and the car really behaved very nicely under the extra passenger and luggage weight.
The car in question here is swift dzire
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Old 28th January 2014, 11:27   #134
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Default Re: The right tyre pressure?

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Originally Posted by mbhangui View Post
My friend has this Volkswagen Jetta 2010 model with the stock 16" alloy wheels. The manual says to maintain the tyre pressure of 32 PSI for two people and 40 PSI when driving with 5 people. The dealer is unable to explain this. Any reason for this wide difference in tyre pressure?
(Remember all the figures used below are fictitious)
Lets say Jetta weighs 2000 lb.
The manufacturer has calculated that this 2000 lb is distributed nicely over all 4 wheels equally.
Also the weight of two people = 400 lb.

Therefore total load = 2400 lb (=600 lb on each tyre)

The tyre pressure is 32 PSI (lb/in2). This means the contact patch on the road at each tyre would be 600/32 = 19 sq inch.

When you load 3 more people (=600 lb), the total weight becomes 3000 lb.
Now we desire to have the same contact patch on the road per tyre = 19 sq in.

How do we get it?
3000/4 = 750 lb at each tyre.
Which means 750/19 = 39 PSI pressure.


Quite close to what VW has recommended ain't it?
Now you have an upper hand over the dealer

The equation is simple: Pressure X area = force or weight or load.
In other words the pressure is defined as: Pressure = Force/area

Actually the tyre pressure of front tyres should be higher than the rear tyres when front seats are occupied. And when rear seat and/or luggage boot is loaded then the rear tyre pressure should be increased. This is because the weight distribution is not equal on each tyre, contrary to what I showed in the example above.

Last edited by alpha1 : 28th January 2014 at 11:30.
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Old 28th January 2014, 12:08   #135
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Default Re: The right tyre pressure?

What's the effect of higher tyre pressure on suspension life ?

Does it significantly reduce the life of the shock absorbers and the suspension mounts ?
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