[saket77]

Nice calc job there Alpha!

But, I have always found it strange (not logically but practically) to alter the air pressure with & without rear passengers. Would it not be better to stick to somewhat an average range or max range of the band to avoid frequent visits to hawawalas?
My car's manufacturer recommends 28PSI. For ages, I have stuck to something in the range of 28-30 with no problems what so ever.

My point is just that it is not practical to alter air pressure every time some friends hop into your car.

Regards,
Saket

[sagarpadaki]

Originally Posted by sdp1975

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 ?

One or two psi above the recommendation will not do any harm to suspension components. More than that will reduce the life of suspension if kept that pressure for long time. But more than suspension going bad, you will uncomfortable driving the car. It will be bumpy

[sukiwa]

Originally Posted by saket77

Would it not be better to stick to somewhat an average range or max range of the band to avoid frequent visits to hawawalas?

My choice is to fill air with my portable air compressor when I venture out for outstation trips with more persons or luggage, no need to visit hawawala.

My point is just that it is not practical to alter air pressure every time some friends hop into your car.

For short distances, it doesn't matter much. But, for long distances it matters. One can't drive loaded vehicle (luggage/passengers) same way as without load if air pressure hasn't been filled correctly. I have experienced this in Innova.

[a4anurag]

Originally Posted by saket77

Nice calc job there Alpha!

But, I have always found it strange (not logically but practically) to alter the air pressure with & without rear passengers. Would it not be better to stick to somewhat an average range or max range of the band to avoid frequent visits to hawawalas?
My car's manufacturer recommends 28PSI. For ages, I have stuck to something in the range of 28-30 with no problems what so ever.

My point is just that it is not practical to alter air pressure every time some friends hop into your car.

Regards,
Saket

Absolutely, if you want to keep away from the hawawallah's, fill in 1-2 psi more than recommended and if possible keep a tyre pressure gauge with you in the car and keep checking it regularly whether you drive single or FULL.

I have been keeping 2 psi more than recommended in all wheels whether I drive single or full.

I keep checking air every alternate day and the main fill-up is every 10-12 days when I tank up.

Anurag.

[alpha1]

Originally Posted by saket77

Nice calc job there Alpha!

But, I have always found it strange (not logically but practically) to alter the air pressure with & without rear passengers. Would it not be better to stick to somewhat an average range or max range of the band to avoid frequent visits to hawawalas?
My car's manufacturer recommends 28PSI. For ages, I have stuck to something in the range of 28-30 with no problems what so ever.

My point is just that it is not practical to alter air pressure every time some friends hop into your car.

Regards,
Saket

I don't think the pressure gauges across the country are accurate enough or calibrated enough to ensure 1 PSI accuracy. So keeping pressure slightly low or high compared to the desired one is anyway going to happen.

[saket77]

Originally Posted by sukiwa

For short distances, it doesn't matter much. But, for long distances it matters. One can't drive loaded vehicle (luggage/passengers) same way as without load if air pressure hasn't been filled correctly.

For this, I stick to the upper range which is 30 PSI for my car. Hence, every time I fill air, I am at the max down to 25-26, which is not too bad and by keeping 30 PSI, car is always ready for full load. BTW, I have a separate gauge and again one on my portable air compressor. Thankfully, readings on both scales are fairly close all the time.

Originally Posted by a4anurag

Absolutely, if you want to keep away from the hawawallah's, fill in 1-2 psi more than recommended and if possible keep a tyre pressure gauge with you in the car and keep checking it regularly whether you drive single or FULL.

Thanks Anurag. Yes, I carry my own air gauge in my car since I have never trusted the tyre shops for it. 1-2 PSI extra will not do any harm and will also give you good FE. Of course, over or under inflation, both are dangerous.

Originally Posted by alpha1

I don't think the pressure gauges across the country are accurate enough or calibrated enough to ensure 1 PSI accuracy. So keeping pressure slightly low or high compared to the desired one is anyway going to happen.

That's well said.
Since, I have a separate pen-type gauge and one on my air compressor too, I make it a point to cross - check with both to be sure. I check air pressure at approximately every 15-20 days.

Wanted to share an incident. My bike, which uses tubeless tires was losing air since last 1.5-2 months. I topped up the pressure about 2 times during the last month. I felt lazy to get it fixed or fix it myself until last sunday. On inspection, spotted the long twisted nail in the tyre and took it out with the help of a screwdriver and a plier. Then used a 'Coido' tubeless tyre repairing kit (Rs. 500/-) to repair the puncture. I must say that the process of inserting the probe cleaner and the rubber adhesive stick is not easy. It takes a lot of effort, but finally fixed it.
(I see that the kit is available at a cheaper price on ebay)

[joybhowmik]

Originally Posted by saket77

For this, I stick to the upper range which is 30 PSI for my car.

I would say keeping it within +/- 2 PSI of recommended pressure is good enough.
Cross-checking with different guages once in a while is good practice.

The other thing, that I do , is to fill up at home with an inflator when the tyres are cold.

Also in case of sudden change in temperature - makes sense to check the pressure. case in point - my drive back to New Delhi from Kolkata. I had filled up to 35 PSI in all 4 tyres when I started from Kolkata - where temperatures were in the 15~20 degree range. When I reached Delhi (next morning after allowing it to cool down, with outside temperature at around 5 degrees), all the tyres reported pressure of 32~33 PSI.
Now one can say that I must have lost that air during the long drive - but I remember having checked the pressure in Varanasi just before leaving for Delhi- and it was exactly 35 PSI at the time - all around. So some of the pressure loss could have been due to temperature differential.

[alpha1]

Originally Posted by joybhowmik

Also in case of sudden change in temperature - makes sense to check the pressure. case in point - my drive back to New Delhi from Kolkata. I had filled up to 35 PSI in all 4 tyres when I started from Kolkata - where temperatures were in the 15~20 degree range. When I reached Delhi (next morning after allowing it to cool down, with outside temperature at around 5 degrees), all the tyres reported pressure of 32~33 PSI.
Now one can say that I must have lost that air during the long drive - but I remember having checked the pressure in Varanasi just before leaving for Delhi- and it was exactly 35 PSI at the time - all around. So some of the pressure loss could have been due to temperature differential.

The pressure will reduce due to decrease in temperature.
Gas law: Pressure X volume = gas constant X no of gas molecules X temperature.

(The volume of enclosure = tyre will stay constant - since it is not like stretchable a balloon, no of gas molecules stay constant in no-leak&losses case, gas constant of course stays constant)

In your case if the pressure was 35 psi @ 17 deg C, then it should be
= 35 x (273+5)/(273+17) = 33 psi @ 5 deg C
Quite perfect match, considering that there would be slight loss of air, thus the "no of gas molecules" should also be taken into consideration, and therefore will yield slightly less than 33 PSI result.

[shashank.nk]

My Swift runs on 195/60 R15 Michelin Primacy LC tyres. Maruti recommends 32 at front and 30 at rear when travelling with 5+ luggage or I think 30 at front & rear if there are only one or 2 passengers.

I've tried 32 on all 4 and found the ride to be too bumpy, but it helped me when I traveled through some very bad roads and hit a few potholes at speed. No sidewall crack luckily!

I got it down to 30 today and the ride has definitely improved but want to know if there are any disadvantages other than FE drop ?

[a4anurag]

Originally Posted by shashank.nk

My Swift runs on 195/60 R15 Michelin Primacy LC tyres. Maruti recommends 32 at front and 30 at rear when travelling with 5+ luggage or I think 30 at front & rear if there are only one or 2 passengers.

I've tried 32 on all 4 and found the ride to be too bumpy, but it helped me when I traveled through some very bad roads and hit a few potholes at speed. No sidewall crack luckily!

I got it down to 30 today and the ride has definitely improved but want to know if there are any disadvantages other than FE drop ?

Isn't that pressures for 185 section tyres?

32 psi in all 4 tyres is bouncy affair, I'd say F-32 & R-30 which works best for me. Since there is more weight in the front a higher pressure on the front set is better to counter balance.

All round 30 psi again is low IMO and since pressure is lower drag is hover so lower FE and better ride due to cushioning.

Anurag.

[srishiva]

When we upsize the tyres (width wise), the recommended tyre pressure given the same loads should be lower, right?

Different tyres with different contact patch characteristics means we cant generalize anything and its safe to have the same set of tyres that manufacturer recommends. This would be absolutely right, however hopefully the changes are within tolerance limits.

[shashank.nk]

Originally Posted by a4anurag

Isn't that pressures for 185 section tyres?

32 psi in all 4 tyres is bouncy affair, I'd say F-32 & R-30 which works best for me. Since there is more weight in the front a higher pressure on the front set is better to counter balance.

All round 30 psi again is low IMO and since pressure is lower drag is hover so lower FE and better ride due to cushioning.

Anurag.

Yes. I forgot to mention that's recommended pressure for 185 section tyres.

I also tried 33 and 30 at front and rear respectively. It was still too bumpy for my liking.

With 30 all round the ride is so much better. Will drive around for 1k kms with this and see if I'm happy

[Requiem]

I need some help.
So a nail got stuck in my car's tyre two weeks back.
The tyre had not been cut on the sidewall and the cut wasn't even deep . I got it fixed within 30 mins of the incident, and the guy who fixed it did it correctly.
So I doubt that there could have been any major damage.
I got it repaired with the plug kit , then got the pressure of all tyres set to 30 psi.
7 days later when I check the pressure , all tyres are in the range of 30-31 psi, except the tyre I repaired, it was on 36 psi , thinking its a one off incident I let it go.
I reset all the tyres to 30 psi and after another week , I encounter the same thing.
All tyres were in the 30-31 psi range except the one I repaired. It was on 35 psi.
This is the first repaired tyre I'm using so its got me wondering !
I know that the tyre pressure increases as tyres warm up after use, but can anyone please explain to me why this one tyre has such high gains in pressure compared to my other tyres ?
Do all puncture repaired tyres behave similarly ?

[a4anurag]

Originally Posted by Requiem

All tyres were in the 30-31 psi range except the one I repaired. It was on 35.

Lol! Cheating physics.

Something wrong here, I guess the tyre guy is wantedly maintaining hover pressure only for that tyre due to the puncture.

Originally Posted by Requiem

I know that the tyre pressure increases as tyres warm up after use, but can anyone please explain to me why this one tyre has such high gains in pressure compared to my other tyres ?

It increases but so much increase in pressure is impossible.

The rest 3 tyres are also rotating in the same way as the affected one so this tyre specifically increasing in pressure due to usage and heat is ruled out.

Originally Posted by Requiem

Do all puncture repaired tyres behave similarly ?

No they don't behave like your car's case. The pressure decreases over time not vice-versa.

Anurag.

[darkbull]

I tried searching online but could not find the exact meaning of PSI. Some places mention it as Pollution ....... Index. How is that related to the air that is filled in the tire

On 1st March, this month, I filled fuel in my Ertiga and got the air pressure checked. Usually I travel alone, but anticipating a lot of travels, I filled ordinary air (35 psi) on all my tires, such that I don't have to bother about it when I travel.

I don't opt for Nitrogen as such, as I was told that the ordinary air also has Nitrogen at 75% and why pay extra for filling Nitrogen in your tires. Also there was no visible benefit of filling Nitrogen except for the air pressure problem of checking once a month.

Coming back to my saga, on 3rd March, I felt the vehicle to pull a little too much. I suspected the front tires losing out air pressure. So I took it to a petrol bunk and asked him to take it back to 35. While he was adding the pressure to the tires, the indicator was showing as if the existing pressure was on 39 . This was in Varthur Indian Oil Petrol Bunk.

The indicator, showed 35 and I was happy. While going back to office, I did not feel a difference or rather I was rushing to login, never paid attention. Returning back home in the night, again I felt the air pressure to be low. Took it to HP Petrol bunk to get the air pressure filled. The air pressure in HP Bunk showed that all the tires had only 31. I was shocked, as I could understand why the pressure was low so soon. Filled it again to 35 and reached home.

The pressure was good. Just out of curiosity, I entered the bunk in Electronic City where I had filled Diesel earlier again for a refill. I filled the fuel and asked him to update the tire pressure to 35. The pressure guage showed the air pressure as 37 for the rear tires and 36 for the front tires. I was not able to guage what could be the problem.

Got it topped till 35 again and on Sunday next week decided to explore this idea of getting air pressure checked across electronic city, hosur road and sarjapur

1. Electronic City - Starting Point - 35 psi all tires
2. Next to brand factory - Bharat Petroluem - Pressure showed 37 on all tires. Readjusted back to 35
3. Bharat Petroluem, Ejipura - Pressure showed 33 on all tires. Readjusted back to 35.
4. Shell Bunk on Bomnahalli - Pressure showed 35 on all tires. So Shell and Bharat Petroluem has the same guage
5. Indian Oil - Kudlu Gate - Pressure showed 39 on all tires. Readjusted back to 35 on the tires
6. Electronic City - Starting Point - Bharat Petroluem - Pressure showed 29. Readjusted back to 35.

Now I completely don't understand, how do we take a measure whether the air pressure on the tires are correct or not.

1. Places on the highway have a mix of all bunks.
2. Air pressure across the same brand of bunks also are not the same.
3. Shell is reliable. But not many on the highway

I wanted to check with the community, the Manufacturer just states 35/33 psi for the tires. The air pressure varies across bunks, how does one assume which one is correct and which is not.


Regards
DB

Note to Mod: - I tried the articles posted, but could not get a match to my query, hence I have created a new one