[Mu009]

Invest in a reliable, heavy duty air compressor + gauge, and go to the "inconvenience" of checking pressures and filling them up yourself (on level ground).
You "waste" time and fuel (idling while running the compressor from 12V socket), and it is more inconvenient (as some I know view it).
But, you don't have to wait in pesky lines at pumps, and most importantly, you get cold, true, SAFE tyre pressure.
Ideally, tyres are your only point of contact with the road. Investing in them - from procurement to upkeep (money and care and your own time) is as important to performance as engines and transmissions, as important to safety as bodyshells and airbags. Really, it seems illogical to me to not bother with this personally.

My two cents anyway.

I use my ViAir 85P for all my vehicles, and check pressures routinely (after a minimum of 12 hours of cool down). I'm certainly not trusting some random fuel pump guy, his level of care, his gauge on hot tyres.

[paragsachania]

Reading your thread, I recollect one instance that I would never forget. It was 2008 and I was driving to Hubli. At a Shell Fuel station before the start of the journey, I tanked up my car (WagonR) and also got the tire pressures checked. I usually set that to 32 or 33 depending on the number of passengers and load and also closer to recommended numbers.

The journey was uneventful but one thing I noticed was that the car would struggle even to hit the 100 KMPH mark and show signs of lethargy if slowed down below 60 KMPH. I didn't have to doubt the fuel assuming that Shell won't cheat me (then).

Things didn't change the next morning as well as we took some internal roads and fast single carriageway sections of North Karnataka. I somehow was getting too irritated that the car is struggling so much. There were no other signs in terms of lighter steering or etc.

However, on the same day, during the second refill, I noticed that all the 4 tires appear bulged more than usual and I quickly asked the attendant there to check the pressure. To my surprise, the pressure in all the 4 tires were between 25-25 PSI .

I asked him to set that to 33 for front and 32 for rear and continued driving back to Bangalore. The difference was instant, and things back to normal and I could cruise happily without a fuss.

Lesson Learnt (like others say): Never rely on the calibrations of the compressors at the fuel station or even a puncture shop guy. It was then that got myself an analogue gauge from my friend who had traveled to Taiwan. The same is now given away to another BHPian friend of mine when he drove to Himachal Pradesh 5-6 years before!

As of now, I have a portable tire inflator but I don't want to remove that and plug it in each time I want to check the pressure. So I have this simple device that is always at the seat back pocket that I pull out and check the pressures when there is a need:



It is very accurate since I compared the readings once at the ASC and second time at a reputed tire shop near my home. It shows pressures in PSI, Bar and KPI. It cost me 499/- then on ebay but now you get loads of options on Amazon and Aliexpress. It runs on a typical CR2XXX coin type battery that I replaced just once in the last 7 years.

For inflating needs, I have my portable inflator that takes care of things anyway.

[antz.bin]

Tyre pressure is to be measured on cold tyres (tyres which have not run more than 2.5 km in the past 2 hours). The reason you got the hyper inflated reading could be due to the fact that you had already run the tyres for 25km and they were warm now. The original value could have been 60-70.

But whatever might be the case, even 60PSI is too high, you should have realised faster.

[Thermodynamics]

Did some browsing on research activities on tire burst testing. As per this reference 90 psi seems ok.



They start with 100 psi and typical bursting pressure is above 250 psi. It is also important to look at plastic strain (right Figure). It seems the plastic deformation kicks at about 1.2 MPa or 170 psi.

These are at controlled testing conditions for a certain type of tire, real time scenarios can be significantly different. Although 90 psi seems to be ok, may be you should do a close observation if there are any bulges/deformation.

Thanks for sharing your case. It in fact emphasizes the need for TPMS as an essential safety feature.

[ThilakNex]

Originally Posted by Miyata

I agree with few of the observations above - many of these places do not have a calibrated setup and give inaccurate readouts. I keep my own personal pressure gauge (analog) as well to monitor the pressures occasionally.
but for such durations, I think the tyres are quite forgiving.

Yes, that's the lesson learnt. personal pressure gauge & monitor is a must-have.

Originally Posted by shipnil

Could be that second guys gauge too is defective.

Originally Posted by sidpunjabi

What about the digital display of the air pump at the 2nd guy? Was that working fine? Many of these digital displays often go for a toss quickly but aren't repaired until the complete air-pump machine goes kaput.

The 1st guy probably overfilled it till 40 which the gauge read but a partially dead display may have shown it as a 90.

Could be, but for the time it took to deflate and the look of the tyre and feel of the ride ensured that second guy's gauge was close to correct if not perfect.

Originally Posted by Mu009

I use my ViAir 85P for all my vehicles, and check pressures routinely (after a minimum of 12 hours of cool down).

Noted :-)

Originally Posted by paragsachania

Lesson Learnt (like others say): Never rely on the calibrations of the compressors at the fuel station or even a puncture shop guy.
As of now, I have a portable tire inflator but I don't want to remove that and plug it in each time I want to check the pressure. So I have this simple device that is always at the seat back pocket that I pull out and check the pressures when there is a need:

Thanks a lot for the information. It would be really helpful if you can suggest a good portable tyre inflator in the market.

Originally Posted by antz.bin

Tyre pressure is to be measured on cold tyres (tyres which have not run more than 2.5 km in the past 2 hours). The reason you got the hyper inflated reading could be due to the fact that you had already run the tyres for 25km and they were warm now. The original value could have been 60-70.

But whatever might be the case, even 60PSI is too high, you should have realised faster.

Completely agree..

Originally Posted by Thermodynamics

Did some browsing on research activities on tire burst testing.
They start with 100 psi and typical bursting pressure is above 250 psi. It is also important to look at plastic strain (right Figure). It seems the plastic deformation kicks at about 1.2 MPa or 170 psi.
. Although 90 psi seems to be ok, may be you should do a close observation if there are any bulges/deformation.

Thanks for sharing your case. It, in fact, emphasizes the need for TPMS as an essential safety feature.

That's really a good insight about the issue. On a positive side, after a day tyre looks absolutely normal with no deformation. Thanks a lot for the information

[sukiwa]

Originally Posted by ThilakNex

It would be really helpful if you can suggest a good portable tyre inflator in the market.

We have a separate thread for portable tyre inflators (Tyre pressure gauge and portable inflator pump / foot pump).
Choose among brand names like ViAir, Windek, ResQtech, Goodyear, Michelin.

[Rahul Rao]

A tire is strong enough to handle 90psi or even more than that.

Even with our normal 30 psi or thereabout the tire can momentarily go to higher pressure due to impact deformation on rough road surfaces. What it cannot handle is a impact when over inflated tire gets squeezed or poked due to road impact when overinflated.


Rahul

[Santoshbhat]

Originally Posted by ThilakNex

I have already driven 25kms from the petrol pump and didn't want to take any risk further. Hopped into yet another fuel pump to check the pressure.
Got shocked to see that previous petrol pump guy had filled almost 90+ psi in all the tyres whereas the recommended pressure is 30 psi

Even though happy for the fact that I noticed the abnormal response from the car (though bit late), I am worried if this overinflation has caused any permanent damage to the tyres given the fact that it has run for around an hour and 25 Kms. Can the experts shed some info on it?

A lot of pumps have badly calibrated air pressure gauges at their premises. While it is very likely that the first pump's gauge understated the pressure, it is also likely that the second pump's gauge overstated the pressure. 90 PSI is not easy to fill. Surely needs a strong pump and a lot of time for each fill to fill up to 90 psi.

As suggested by others it is highly recommended to keep your own pressure gauge in the car to maintain correct pressure. Always remember to check pressure when tyres are cold. 30 psi cold becomes almost 36 ~38 psi after running for some 50 kms on the highway. Check pressures periodically to get notified of any slow leaks in any of the tyres. Believe me you don't want your tyre to slowly leak air when you are starting on a 1000 km long drive. You may check pressures while starting, but halfway through your journey your tyres will be underinflated. Underinflation is the number cause of tyre bursts. And lastly remember to check your hand held gauge's calibration periodically. It does not hurt to keep a good quality spare gauge to use only as a master gauge for checking the correctness of the first gauge.

[SnS_12]

Normally I have noticed is the air pressure gauges used by the local Tyre shops show a lower reading. So if it shows 30 psi the actual pressure is around 40 psi.

Hence, I invested in a digital goodyear tyre inflator and am a happy customer for the past few years. Normally I check the pressure once in two weeks and top it up on my bikes and car. Also, I have noticed putting valve caps help reduce air leak to an extent.

[Hatari]

Use Nitrogen next time. Its too expensive for them to ever over inflate!

[saket77]

Originally Posted by Hatari

Use Nitrogen next time. Its too expensive for them to ever over inflate!

Gone are the days. Nitrogen filling is free at most pumps.

Bad maintenance and over & improper usage beyond the intended life is why most gauges used by public filling stations are incorrect. Best bet is to have one of your own.

Regards,
Saket

[vipul_singh]

The Michelin XM2s come with a warning embossed on the sidewall: 'Do not inflate over 50psi'. Would be prudent on the OP's part to check if the tyres on his / her car came with such a warning, and if so, what is the implication of going over the limit.