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Old 7th October 2009, 15:53   #31
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Tyre pressure dropping

My tucson is running on 235/60/R16 Michelin latitude tyres on stock rims for the last 15000 kms. I usually inflate the tyre with the recommended 30psi of pressure and no nitrogen. But, always after a weeks time, I find that one of the 4 tyres has lost some pressure. I check and correct the tyre pressure again, but then again the pressure drops in one tyre after a few days. The under inflated tyre seems to be chosen randomly as any one can lose pressure. If this week it is the rear left one then last week it was the front right tyre. The drop in pressure is visible and when checked it will show around 20 psi while other 3 would have retained 30 psi each.

What is causing the problem? I havent rotated the tyre. i always check the tyre pressure from one place. i have tried other places too just in case its a problem with my usual pump. the tyres have no puncture yet and still looks very much new. I took it once to a tyre shop and they tried filling and checking it with 50 psi of air, but couldnt find any leak. But this is going on since i put these tyres in and even today one of the tyres is under inflated!
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Old 7th October 2009, 15:56   #32
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How are the rims, assume that they are alloys. Any defects on the edge? Hope you dont have any naughty kids around your parking area?
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Old 7th October 2009, 15:58   #33
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So you are saying sometimes its one tire that loses pressure, sometimes its other, right
This does not mean the tire has a problem, it means somebody is playing hanky panky with you.
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Old 7th October 2009, 16:10   #34
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Tyre pressure increasing!

I have the reverse problem!

When I check the tyre pressure in my Palio 1.6 (30 psi in front, 29 psi at the back) once in 2 weeks, the right front tyre shows an abnormally high reading of about 38-40 psi, even though the distance to the petrol pump is hardly 1 km. The remaining 3 tyres's reading hovers around 1-2 psi less than what was filled last time.

Funny thing is, while driving, it doesn't seem that 1 front tyre is overinflated; the car doesn't pull to one side, steering isn't stiff, ride isn't bouncy - nothing. Visually also, it doesn't seem to be bursting at the seams.

This has happened twice in the last 1 month and I'm a bit puzzled by this behaviour. Can any Gurus shed some light on why this may be happening, and how to resolve it?

EDIT: VEA, my apologies for hijacking your thread!

Cheers,
Vikram

Last edited by comfortablynumb : 7th October 2009 at 16:11.
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Old 7th October 2009, 16:13   #35
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Quote:
Originally Posted by vishnuvijay View Post
one of my Kumho Ecsta AST KU25 tubeless trye is loosing air pressure very fast. i corrected the air pressure to 30 psi and 2 days later i found it to be 11 psi. filled in air again, the guy at the ioc pump said there is no leakage.

went on a trip (300 km (first day) + 300 km (second day) ) checking air pressure in between and found it not to be decreasing. came back home and the next day ( again 2 days passed since i last filled it) found that a good amount of air has escaped.

is it a puncture or is there something else wrong.
Same thing happened to me just a month back, after lot of prob found out that an old puncture was the culprit. Although when i went to tyre shop for getting it checked there was no leakage but then i asked the person to fill some extra air and then check, then i came to know that one of the old puncture was leaking. Better get your tyre checked.
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Old 7th October 2009, 16:19   #36
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@comfortably numb, touch tires after a drive. If this tire is hotter, it could mean either brakes are touching the rotors, or the bearings are shot.
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Old 7th October 2009, 16:20   #37
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@Travel bug: VEA the problem occurs in different tires, unless all of them have some foreign elements in them or the neck/neck seating at fault, it shouldnt happen.

@VEA: Check the valves, and hope you are running valve caps. Dust and dirt inside the valve's might cause leakage.

@comfortablynumb: Have you tried using another filling station with an electronic set up. I have figured out that there can be huge variations between meter to meter. In my case my old pump shows 34 and the new one will show 38. So stick to same filling equipment and dont let the attendant hurry with the filling, wait for the beep and again wait for 2-3 seconds before they move on to next wheel.

@tsk: 1 km running even without any bearings or completely jammed brakes will not increase PSI by 10 pounds.

Last edited by Jaggu : 7th October 2009 at 16:21.
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Old 7th October 2009, 16:27   #38
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Quote:
Originally Posted by Jaggu View Post
@comfortablynumb: Have you tried using another filling station with an electronic set up. I have figured out that there can be huge variations between meter to meter. In my case my old pump shows 34 and the new one will show 38. So stick to same filling equipment and dont let the attendant hurry with the filling, wait for the beep and again wait for 2-3 seconds before they move on to next wheel.
I will do that. Thanks!

@tsk1979 - I will do what you suggested too, just to be on the safe side. One question though - if the brakes were even slightly jammed or touching the rotor, wouldn't the pick up seems sluggish? That's doesn't seem to be the case at all here.

Cheers,
Vikram

Last edited by comfortablynumb : 7th October 2009 at 16:34.
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Old 7th October 2009, 23:25   #39
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Quote:
Originally Posted by Jaggu View Post
How are the rims, assume that they are alloys. Any defects on the edge? Hope you dont have any naughty kids around your parking area?
The rims are stock alloys in excellent condition. No defects on the edge.

Quote:
Originally Posted by tsk1979 View Post
So you are saying sometimes its one tire that loses pressure, sometimes its other, right
This does not mean the tire has a problem, it means somebody is playing hanky panky with you.
I considered this. I have no kids at home or in the neighbourhood. My car is parked at home in such a way that the left side is so close to a wall and nobody will pass through and reach the tyre. At work its parked in my factory premises which is quite safe and secure and child free.

Quote:
Originally Posted by comfortablynumb View Post
EDIT: VEA, my apologies for hijacking your thread!
Fine with me numb, as long as your problem stays away!

Quote:
Originally Posted by Jaggu View Post
@VEA: Check the valves, and hope you are running valve caps. Dust and dirt inside the valve's might cause leakage.
All valves have caps and checked atleast 2 times at tyre repair shops. They filled the tyres with 50 psi and found no air leak. The tyres wont lose more than 10 psi and it is drivable even after losing that pressure.

Is there a chance that the tyre is ill fitting on the rims and thus lose air when hitting edges, kerbs or something? I had 215/65/R16 tyres earlier on the same rim with no issues. I now have 235/60/R16 on stock tucson rims which looks a bit ballooned.

Last edited by VEA : 7th October 2009 at 23:27.
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Old 8th October 2009, 10:15   #40
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Aha! Thats the culprit. If your rims are not designed for such thick tires, you will have trouble.
For example if your rims are 5J and tire says minimum 6J required, you could be leaking air during cornering.
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Old 8th October 2009, 11:03   #41
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Quote:
Originally Posted by tsk1979 View Post
Aha! Thats the culprit. If your rims are not designed for such thick tires, you will have trouble.
For example if your rims are 5J and tire says minimum 6J required, you could be leaking air during cornering.
Yup possibility, so check what is your Rim width first but since its an SUV it would be quite wide.
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Old 8th October 2009, 19:51   #42
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Quote:
Originally Posted by Jaggu View Post
Yup possibility, so check what is your Rim width first but since its an SUV it would be quite wide.
I checked one of the wheels. It says 6.5Jx18-46, which in my guess means 6.5J. Is it enough to hold a tyre of the size 235/60/R16?
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Old 8th October 2009, 20:09   #43
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Tucson user manual says the same alloys can take 2 tire sizes.

215/65/R16 - Stock tire size

and

235/60/R16 - Comes in Elite variant (US Spec)

So I guess your upsize is not the real culprit here.

BTW do you see any major difference in performance/braking/cornering after switching to 235/60/R16?. My Tuc's tires are due for change in the next 10K Kms or so and wanted to know if there is considerable difference after the upsize.
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Old 9th October 2009, 00:42   #44
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My car was running on the stock hankook tyres before upgrading to michelins. The major difference is the brakes. The wider tyres really bite on to the tarmac. The ride seems to be marginally cushioned too.
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Old 9th October 2009, 09:43   #45
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6.5J is good enough. So another question, I think this is an alloy rim?
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