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Old 19th November 2007, 21:17   #46
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Originally Posted by mansidea View Post
This is one thread which i was searching for. You can always stick to the OE tyre pressure when your are on OE tyres. Most of the questions here are regarding an upgrade. I recently changed the 235/75/15 bridgestones (with tube) of Scorpio to 255/70/15 Michelin tubeless. The OE tyre pressure is 29/31 for the front & rear tyres respectively. I used to keep all at 29 as i drive alone mostly. I am continuing with 29 for the new set & now the question is, should i increase or decrease the pressure as the Size of the tyre has changed. The guy who did the wheel alignment suggested to reduce the pressure when you increase the size with some logic which i couldnt follow. what do you guys say?
Dear all

OE recommends Inflation pressure keeping so many factors in mind, they reach to this inflation pressure by undergoing so much R&D. Always stick to OE recommended pressure.

Actually inflation pressure works on PRESSURE VOLUME WORK DONE THEORY i.e. work done by air inside tyre = Pressure X Volume. So as the the volume increases, the pressure is to be reduced keeping the load same. Altough i have not been able to figure out the amount of change.
Examlpe:Hyundai's Santro, Accent, Sonata all three vehicles had 30 psi as recommended pressure.

Deviation: Whenever there is deviation from required/recommended pressure there will be excess wear on tyres.
Low I/P: low I/P will result in excessive heat generation in tyres and wear on the tyre shoulders will be more.
High I/P: will result in faster wear in the centres.

Highway driving: Whenever going for highway highspeed driving, always overinflate your tyres by 3-5% . This would avoid excessive heat generation in such conditions avoiding heat failures.

Happy and safe motoring.
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Old 19th November 2007, 21:43   #47
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upsize = less psi

ideal settings? play around a lil bit and you will figure out
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Old 20th November 2007, 12:34   #48
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Thanks & that was news to me.
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Old 3rd January 2008, 16:27   #49
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Whats the recommended air pressure for Swift Diesel having upsize 195 60 R15 Michelin MXV8 for Bangalore city drive.
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Old 3rd January 2008, 17:05   #50
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Originally Posted by Ajaybiz View Post
Whats the recommended air pressure for Swift Diesel having upsize 195 60 R15 Michelin MXV8 for Bangalore city drive.
30 psi should be fine. If u find the ride is bouncy then reduce to 28psi.
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Old 3rd January 2008, 17:45   #51
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In such case :
Original size 165/80 R14
Upgradation : 195/60 R15

2psi less than OE recommended pressure should work good.
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Old 7th January 2008, 11:06   #52
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For Original size 165/80 R14 OE recommended pressure is 36 at front and 33 at rear so filled 34 at Front and 31 at rear day before yesterday as i got 195's and looks like its quite OK no bumpy rides.
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Old 7th January 2008, 13:12   #53
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Originally Posted by itzzme View Post
Highway driving: Whenever going for highway highspeed driving, always overinflate your tyres by 3-5% . This would avoid excessive heat generation in such conditions avoiding heat failures.
I am under the impression that during highway driving the pressure increases due to heat. This may cause reduction in grip etc. So it is better to fill to recommended pressure only before a highway drive. Whereas in city we can fill 2 or 3 psi more than recommended. Could experts please guide?
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Old 23rd January 2008, 14:12   #54
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Hey all,
what tyre pressure should i maintain?

Tyre Size----Tyre Pressure
Original - 165/80 R14----29 Front / 26 Back

New - 205/55 R15----29 on all four

The new tyres are pretty stiff and the compound is as well. This is leading to a harsh and bumpy ride.
Should i change the pressure i am using? (29 on all four)
Car - Opel Astra
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Old 13th February 2008, 20:41   #55
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just the thread i was looking for - hope i get some responses.

got myself a tubeless BridgeStone for my alto.

Filled up 30psi, as recommended, and noticed that the ride was bumpy. have reduced the front to 28 and back is at 30.

hope the ride is smoother - will check and let you know tomorrow.

Itzzme,
as responded by muragavel, does not long drive (aka highway drives) increase the temperature in the tire, hence causing it to expand and finally an increase in pressure. Is this not the reason that experts always advice to check / fill tyre only when its cool? I reckon your advice is wrong.
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Old 14th February 2008, 16:53   #56
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Quote:
Originally Posted by Xehaust View Post
Hey all,
what tyre pressure should i maintain?

Tyre Size----Tyre Pressure
Original - 165/80 R14----29 Front / 26 Back

New - 205/55 R15----29 on all four

The new tyres are pretty stiff and the compound is as well. This is leading to a harsh and bumpy ride.
Should i change the pressure i am using? (29 on all four)
Car - Opel Astra
Had posted my query before,
Played around a bit and have come to the conclusion of 28 Front and 27 or 28 Back.
This is for the Summer. The ride has become much more comfortable than before.

We have been experiencing cold weather recently and therefore i have been filling 29 Font & 28 Back. My ride has become much more comfortable.

So i would like to point out that we should fill 1 or 2 PSI extra in cold weather as tires do not generate a lot of heat as in summer and hence the air in the tyres do not expand as much.

In summer, heat is high and air expands rapidly, thereby we should fill lower than compared to winter as the expanded air results in higher PSI.

Ans would also like to stress on the fact that always fill your tyres when they are cold i.e. ideally you have not gone more than 4-5 kms from standstill.

Hope this helps
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Old 17th February 2008, 18:48   #57
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Interesting !!

I have 225/45/17 on my Octavia running 30 psi all 4. This is up from 195/60/15 (OE) Is this the correct pressure ?? The tyre wall ht has reduced but not the OD.

Intend to change 205/55/16 to 225/50/16 on the A4. Guess here the pressure should be as advised in manual as the rim dia is not changing & neither is the wall height.

Any informed suggestions ??

Cheers
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Old 18th February 2008, 03:28   #58
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Ricky, like mentioned earlier. Stick to the recommended pressure even after upgrade.
Change it only if you find a substantial difference in ride quality (Eg. extra bumpiness).
If plan to change it, there is no fixed calculation. My suggestion would be to not go more than 2 psi higher or lower.
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Old 18th February 2008, 09:11   #59
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On my Ikon 1.3 , i maintain 30 psi on all tyres.....
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Old 18th February 2008, 09:33   #60
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Quote:
Originally Posted by murugaveln View Post
I am under the impression that during highway driving the pressure increases due to heat. This may cause reduction in grip etc. So it is better to fill to recommended pressure only before a highway drive. Whereas in city we can fill 2 or 3 psi more than recommended. Could experts please guide?
If you are planning to do high speed driving fill 2-3PSI More than recommended. Do the filling up when the tire is cold
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