[jeganatu]

This why I always prefer the manual receipt given by the toll plaza which is no more available. The back side of the receipt contains important numbers like Plaza manager, ambulance, rescue vehicle or breakdown assistance. I have once used the amulance number to report an accident which happened just 4km off the toll plaza.

Now with fastag, one may have to look for the board having the emergency number which is a pain.

I would suggest NHAI to send important numbers of that toll plaza along with the toll receipt sms to the owner of the passing vehicle.

FYI , I have saved all the toll plaza numbers of my regular travel route for emergencies.

[Rshrey22]

Originally Posted by Strider24

Options which I am now considering:

1. Buy a continental cc5 tyre which is the nearest to Michelin in terms of soft compound and low rolling resistance. Use it along with the spare tyre and put them both in the rear (my spare tyre came brand new when I bought this car) and put the best 2 out of 3 Michelin tyres in the front. This was advised by the Continental dealer in Bhopal on call, and also sounds logical to me.

2. I buy a locally available Bridgestone and use it along with a new spare tyre in the front and keep the front right tyre which has around 15k running back in the trunk as spare.

In this option, I need recommendations to choose which Bridgestone model should I choose which has a softer compound and can be paired with the new Michelin P3ST. Also, it is recommended to pair two different brand tyres on the front? Or shall I keep them in the rear?

Currently, both rear tyres have run around 22k km and are in good condition.

A quick recommendation from the above two options or maybe a better alternative is highly appreciated as I have to travel back to Pune in 10 days and I can't risk travelling 1250 km without a spare tyre.

Thanks a lot.

Go for Continental CC6, I have them installed in my Wagon R upsized to 175. They are quiet but not very good on handling and comfort.

If you want the absolute best that a tyre can offer, Go with Bridgestone Turanza Series (Er60, T001, T002) they are absolutely quiet on road (all you will hear is the engine) provide comfortable ride, and great handling.

I tested them through their paces in my Dzire while returning from Shimla (roads are twisty and smooth, so perfect for cornering etc).

Also, really happy that no untoward incident happened during your journey, have a safe ride ahead!

[norhog]

Originally Posted by Strider24

https://Youtu.be/tuo9vDlirGA

Thanks a lot.

Really pleased to see all of you folks to have a luck escape from a potentially dangerous occurrence.

There was a brick on the road that led to this incident.

On a lighter note, the sound of the tyre hitting that brick on the road and eventually giving way is kind of in sync with the music in the video clip.
First time I saw the video, the thump of the tyre burst, I thought it was part of the music when the beats start kicking in after melody.

[clement.lloyd]

Couple of days back, Me and my family members(total 5 of us) travelled from Chennai to Madurai covering over a distance of ~540 Kms to attend to a medical emergency.

Our Honda city 2018 V MT, with its stock tyres MRF - ZVT 175/65/R15, had done close to 20K kms in a span of 4 years. The tyres looked close to good and always gave me the impression that they still have a lot of life still left.

Since all of were in a hurry, after hearing a very sad news, we had to start quickly from home. As usual, I ensured that I do a quick check on my tyres and inflate them if required. This time I set 33 PSI on all the four tyres (whereas the recommended tyre pressure is 32 - front and 30 - rear). Not sure what I was thinking, but all I had in my mind was that I had to be driving above my average driving speed (which is 80 km/h) to reach our destination earlier and probably wanted to be a bit extra precautious.


Travelling half way through, when I went past 90 km/h, I sensed a good amount of vibrations on the steering and on my the accelerator pedal. Everyone else in the car was comfortable, and I was just thinking to myself if this is what I would get from a Honda after 4 years of ownership(My dad anyway keeps complaining that the car makes a lot of noise when driven at high speeds).

Rewinding a few days back, I had found this part under my car(the pic is from boodmo):



Blame my carelessness/ignorance, I initially thought of throwing this away, but decided to put it in my trunk because it looked something that belonged to my car, just that did not know what it was, the underbelly was tidy and neat.

Coming back, 30 minutes into the drive we noticed that water from the AC was dripping on to the passenger compartment. I stopped the car and to my surprise there was no connection between the AC water outlet and outside of the car. This is where it stuck me that the hose pipe in the trunk is the connector that may have slid off. I did not want to spend any time fixing this and immediately, turned off the AC, opened the windows and set off again.


30 minutes away from the destination, it started to rain heavily and soon my visibility was greatly reduced, due to the rain/darkness and the fog that kept coming back on the windshield from the inside. Thanks to our roadway authorities, I managed to sight a speed breaker on a detour and slammed at it at about 30-40 km/h. The impact was pretty bad, and soon we could feel a lot of vibrations on the pedals/steering/passenger compartment. I now sensed that the front tyres/suspension may have dealt a great deal of damage.

We kept going. Constantly below 40 km/hr, citing prayers. Was slow and steady on the accelerator and no sudden braking. We reached our destination at around 10:15 PM. I called Honda RSA. I was promised assistance within an hour. Since it was already 10:30 PM in the night, I told them that I was fine if the assistance reached me the next day morning at 8:30 AM and that is when I would be returning back to Chennai. I parked the car and did not want to look at the damages during the night :(.

The following day, I had a look at the tyre, the rear right tyre had severe damages.




The damage,




The dealer advised me to change all the four tyres. They said that the tyres had crossed their limits and should be changed. Thankfully there were no damages to the suspension or other parts.

I agreed, mostly because I wanted to be safe and safety is my topmost concern. At the same time, I wanted to upsize as well. I asked the dealer to replace the damaged tyre with the stepney and went to a nearby tyre dealer and switched to Yokohama 195/60/R15.


Throughout this process the Honda RSA team were amazing, kept reassuring me and following up until I told them that everything is fine now.


Reflecting back, I probably made a lot of mistakes,

- Over inflating the tyres other than the recommended setting.
- Driving at around ~100 with the stock MRF tyres.
- Neglecting fallen parts near my car (poor awareness).

I am grateful to God that nothing untoward happened that night and everyone is safe. Hopefully this post is useful for.

My return journey was pleasant. I shall write a separate review on my new tyres.

[Thad E Ginathom]

Originally Posted by clement.lloyd

This time I set 33 PSI on all the four tyres (whereas the recommended tyre pressure is 32 - front and 30 - rear).

Isn't it said that it is safer to over-inflate than to under-inflate?

[clement.lloyd]

Originally Posted by Thad E Ginathom

Isn't it said that it is safer to over-inflate than to under-inflate?

Honestly, I am not sure. I have been consciously setting the recommended tyre pressure(whenever I go on a long trip) over the past few years with the stock tyres and have not faced any problems. However, there have been many instances where I have over inflated(when riding in the city) as well and not faced any issues.

So I am not sure, if it was a combination of riding at at high speeds + slamming on the speed breaker(with the stock tyres) that caused this incident, rather than over inflating being the cause.

[RubberGuru1113]

Originally Posted by KuvamBansal

Hi RubberGuru,
Request if you help me with the below query.

I recently installed an external TPMS in my Kushaq and wanted to understand from you regarding how high the temperatures of the tyre reach when being driven. Also, at what temperature range should the alarm bells start ringing and is high temperature a precursor to a tyre burst?

Kushaq rides on standard 16inch 205/60 alloys.
Thanks a lot in advance for your help.

Hello! Tyres can reach a temperature around 25~30 degrees higher than the ambient atmospheric temperature. So on a hot day in North India where it can touch 45~47, it can hit 75 degrees without cause for any alarm. Rubber properties start degrading only above 90 degrees which tyres are never going to reach.

Contrary to popular opinion, tyres do not burst due to "high pressure" like a balloon - at least in the passenger vehicle category, where the max pressure the tyre is designed for is 51 PSI, which again nobody in their right mind is going to fill. You might have read reports of many tyre bursts on the Yamuna Expressway when it opened, which would mention that concrete roars induce more heat than tar roads and this is the culprit.

There is a bit more to this - heat by itself is not going to cause a tyre burst - as long as there is no component separation which has already initiated in the tyres - but this is impossible to know because early stages of component separation are rarely visible outside.

High temperatures cause the air inside to expand and the pressure increases by approx 1.5 PSI for every 10 degrees. This means that after, say, an hour of continuous driving, if you are topping up the pressure on your tyres, you should factor this in and inflate it to 3~4 PSI above your normal pressure. When you park your car in the shade for a couple of hours after doing it, the pressure would drop back to normal levels. This is called "cold pressure" and this is what you need to be maintaining. Coming back to the cause of tyre bursts, it is a combination of high speed, high temperatures and lower than normal pressures, which would cause the tread and sidewall to flex at a high frequency and induce separation of the components like belts, tread, etc. If you take care of your pressure and drive at moderate speeds (not excessively high like 140+), you can rest easy. Case in point - Honda recommends a 3 PSI higher pressure if you are driving at high speeds.



So in a nutshell, high pressure is never the problem (unless you are at excessively high pressures like 45+ PSI where you will start losing grip because of the reduced footprint size, and of course also comfort), it is almost always a combo of low pressure and high temperature.

[Shubz]

Originally Posted by RubberGuru1113

So in a nutshell, high pressure is never the problem (unless you are at excessively high pressures like 45+ PSI where you will start losing grip because of the reduced footprint size, and of course also comfort), it is almost always a combo of low pressure and high temperature.

What if the recommended pressures themselves are close to 44 PSI (as in the case of my F34, GT)

Isn't it recommended to maintain the pressures indicated by the manufacturer?

Thanks

[RubberGuru1113]

Originally Posted by Shubz

What if the recommended pressures themselves are close to 44 PSI (as in the case of my F34, GT)

Isn't it recommended to maintain the pressures indicated by the manufacturer?

Thanks

Firstly these pressures are for RFTs where the footprint shape and overall stiffness does not change much w.r.t. the pressure maintained because of the rigid sidewalls. Excessively high pressures are recommended for full load conditions to protect RFTs from the sort of damage we see on the forum frequently => https://www.team-bhp.com/forum/tyre-...e-upgrade.html (BMW 530d M-Sport (G30) : Tyre upgrade)

On RFTs, these high pressures will also not affect the riding comfort to a large extent.

However, when someone has switched to Tubeless tyres on vehicles that come with RFTs, even though it is very counter-intuitive, it is not recommended to go for such high pressures, reason being that there is a huge differential in tyre stiffness between 35 and 44 PSI for tubeless tyres and not so in the case of RFTs. I had recommended something on similar lines to a fellow BHPian who had changed to tubeless on his G20 where his recommended pressure at full load was 46 PSI.

Originally Posted by RubberGuru1113

Hello! I tried to get the G20's tyre pressure sticker from google and it shows that full load pressure recommendation is 39(front)/46(rear)

Attachment 2356659

Since you are based in pothole-ridden Bangalore, I suggest that you amp up your 1~3 pax pressure to 36 PSI all round and for 4~5 Pax, go for 39 PSI all round. If your luggage weighs more than 50 kg, increase the rear pressure to 42 PSI. 46 is overkill no matter what BMW recommends and there's the risk of the tyre wearing out excessively in the center compared to the sides at high pressures.

Most important thing is to always inflate your tyres when they are "cold" - that is, they should not have been driven more than 1-2 km (non spiritedly ) and it should be done in the evening or early in the morning before it gets hot, and your car should not have been parked in the hot sun ideally.

In a crunch, if you do have to top up the pressure in hot conditions after continuous driving, set it to a value that is 3 PSI higher than what I had mentioned above.

As a tyre industry professional, I would strongly dissuade you from going for 33 PSI and there is a scientific reason. the sidewall height for 225/50R17 is only 112.5 mm (when not under load), and subtracting the rubber part on the tread and the bead, it comes down to just under 80 mm.

The unit deflection of the tyre under load goes up by 25% @ 33 PSI compared to @ 36 PSI. Considering a pothole size of 50 mm (of which there are many in bangalore), in order to avoid impact damage on the inner side of the tyre, the loaded sidewall height has to be at least more than that 50 mm value, which would happen only at 36 PSI for a load of 600 kg per tyre (which would correspond to the full load condition of the BMW 3 series). On the other hand, we do not top up the pressure every day, and the average pressure loss is 1~1.5 PSI per week depending on type of usage. This is how I came up with the value 39, assuming a bi-weekly air top-up schedule which means at no point are his tyres at a pressure below 36 PSI.

To help understand how low pressure causes impact damage on potholes (especially for low profile tyres), I 'm attaching an image of how the tyres would deform so that you can visualize better.

Attachment 2356670


Hope this helps!

In a nutshell - yes, it’s safer to over inflate than under inflate, but at the same time, 42+ PSI is overkill for most sizes for non-RFTs even on full load

[Shubz]

Originally Posted by RubberGuru1113

https://www.team-bhp.com/forum/tyre-...e-upgrade.html (BMW 530d M-Sport (G30) : Tyre upgrade)

In a nutshell - yes, it’s safer to over inflate than under inflate, but at the same time, 42+ PSI is overkill for most sizes for non-RFTs even on full load

Thanks for the response sir. Totally agree with your recommendation of not going for RFT recommended pressures for TL Tyres.

Quoting you: "Since you are based in pothole-ridden Bangalore, I suggest that you amp up your 1~3 pax pressure to 36 PSI all round and for 4~5 Pax, go for 39 PSI all round. If your luggage weighs more than 50 kg, increase the rear pressure to 42 PSI."

I am assuming the above suggestion was for the RFT's on the G20,

How does this compare with the pressure recommendation for the F34 I had shared earlier? Mine are on 225/50 R18 W

Thanks.

PS: apologies to the OP if I am hijacking his thread.

[RubberGuru1113]

Originally Posted by Shubz

Thanks for the response sir. Totally agree with your recommendation of not going for RFT recommended pressures for TL Tyres.

Quoting you: "Since you are based in pothole-ridden Bangalore, I suggest that you amp up your 1~3 pax pressure to 36 PSI all round and for 4~5 Pax, go for 39 PSI all round. If your luggage weighs more than 50 kg, increase the rear pressure to 42 PSI."

I am assuming the above suggestion was for the RFT's on the G20,

How does this compare with the pressure recommendation for the F34 I had shared earlier? Mine are on 225/50 R18 W

Thanks.

PS: apologies to the OP if I am hijacking his thread.

The BHPian had in fact switched to TL from RFTs and my suggestion was in line with that. I understand my response to the previous post was a little confusing, I had unly addressed the "upper limit" pressure of 44 PSI. Let me try to give you a more complete answer :-

Like I mentioned before, RFTs due to their rigid sidewall would have a very low differential in stiffness across the pressure range whereas for tubeless tyres it varies wildly between 30 PSI and 44 PSI.

The size fitted on your F34 - 225/50R18 - has the same sidewall height as the BHPian with the G20, who was on 225/50R17, which means the recommended front pressure for 3 pax (32 PSI) is too low for the same reason - while at low pressures, RFTs would prevent the sidewall from flexing, there is no such safeguard on non-RFT tubeless tyres, which is why I had recommended that he maintain 36 PSI all round as against the recommended 33 PSI.

To summarize, while switching from RFTs to non-RFTs, the lower pressure limits need to be increased whereas the higher pressure limits need to be decreased from the OEM recommendation for RFT tyres. The thumb rule is to never let the pressure drop below 32~33 PSI, and assuming an air top-up frequency of once/month and a pressure loss of ~1.5 PSI/2 weeks, this is what I recommend:-

Upto 3 Pax: 36 PSI all round
5 pax: 39 PSI all round
Luggage exceeding 50 kg - add 2~3 PSI to the rear

Cheers

[Shubz]

Originally Posted by RubberGuru1113

The size fitted on your F34 - 225/50R18 - has the same sidewall height as the BHPian with the G20, who was on 225/50R17, which means the recommended front pressure for 3 pax (32 PSI) is too low
Cheers

Let's not compare RFT pressure vs TL pressures please. It totally confuses me.

I am on RFT's - Continental ContiSportContact SSR

My query which you partly answered - recommended front pressure for 3 pax @32 PSI is too low.
1) why would the manufacturer recommend a low pressure?
2) what in your opinion are the correct pressures for our conditions.

Thanks,

[Thad E Ginathom]

Originally Posted by Shubz

2) what in your opinion are the correct pressures for our conditions.

I don't know if this is the right thread for general tyre questions, but I'd like to expand that one to:-

...and how do "our conditions" affect tyre pressure

[RubberGuru1113]

Originally Posted by Shubz

Let's not compare RFT pressure vs TL pressures please. It totally confuses me.

I am on RFT's - Continental ContiSportContact SSR

My query which you partly answered - recommended front pressure for 3 pax @32 PSI is too low.
1) why would the manufacturer recommend a low pressure?
2) what in your opinion are the correct pressures for our conditions.

Thanks,

For one, the vehicle manufacturer recommends the pressures at which the dampers have been tuned for the vehicle. These are pressures at which the vehicle would offer you the optimum balance of comfort and handling performance - there’s no arguing against that. However, in a few cases - especially sizes with extremely short sidewalls (low aspect ratio tyres, sidewall height lower than 115 mm as a thumb rule), it’s better to compromise slightly on the comfort to amp up the pressure and exponentially Reduce the possibility of tyre damage. I had explained scientifically on the answer I had linked you to, re-iterating here :-

there is a scientific reason. the sidewall height for 225/50R17 is only 112.5 mm (when not under load), and subtracting the rubber part on the tread and the bead, it comes down to just under 80 mm.

The unit deflection of the tyre under load goes up by 25% @ 33 PSI compared to @ 36 PSI. Considering a pothole size of 50 mm (of which there are many in bangalore), in order to avoid impact damage on the inner surface of the tyre, the loaded sidewall height has to be at least more than that 50 mm value, which would happen only at 36 PSI for a load of 600 kg per tyre (which would correspond to the full load condition of the BMW 3 series). On the other hand, we do not top up the pressure every day, and the average pressure loss is 1~1.5 PSI per week depending on type of usage. This is how I came up with the value

The full post is here - please check once for pictorial representations which would help you understand better => https://www.team-bhp.com/forum/tyre-...ml#post5397816 (RFT to Tubeless switch for BMW 320d)

This brings me to your second question - what is the “correct” pressure for our conditions? The short answer is that it depends on the tyre size.

For example, Maruti recommends a pressure of 29 PSI front and rear for their Baleno which comes on 2 sizes - 195/55R16 (107 mm sidewall height) and 185/65R15 (120 mm sidewall height). On the 15 inchers, I would encourage you to stick with Maruti’s recommendation. However, on the 16 inchers, I would urge you to increase the pressure by 3~4 PSI to reduce the likelihood of tyre damage for the reasons I stated above. If this is done, at worst your tyre pressure would be 28~29 PSI when it is time to top up, as opposed to ~26 PSI - which wouldn’t be a big issue on the taller sidewalls on the 15 inchers but is a ticking bomb on the low profile 16 inchers.

Considering the high cost of tyres on luxury cars - where most tyre sizes are of short sidewalls and low profiles - lack of a customer friendly warranty policy of most brands for these sizes - and the fact that the majority of them are not even equipped with a proper spare, I’d say that it is better to be safety first when switching to non-RFTs and operate at a higher pressure.

Originally Posted by Thad E Ginathom

I don't know if this is the right thread for general tyre questions, but I'd like to expand that one to:-

...and how do "our conditions" affect tyre pressure

This is an excellent question. The obvious connection is that the combination of low profile tyres and pothole ridden roads demands higher pressures like I explained above (for the reason that you’d want the tyre to deflect less per unit load on bad roads). Sometimes people do the exact opposite because they have heard that heavy off-roading requires one to decrease the pressure - the difference is that tyres made for off roading have extremely tall sidewalls which means little or no chance of low pressure related impact damages, unless the tyres are almost flat. Plus, in extreme terrain, the tyres operate at low speeds and perform best when they have the biggest contact area - which demands low pressures. One must note that the pressures should be increased back to normal once the vehicle hits the road.

Other than this, tyre pressure (which is a differential between atmospheric pressure and pressure of the air in them) should be increased at higher altitudes because the atmospheric pressure is low. At sea level, atmospheric pressure is 14.7 PSI (with a rough decrease of 1~1.5 PSI every 1000m). So a “gauge pressure” of 35 PSI means an absolute pressure value of 49.7 PSI at sea level, and if you take your vehicle to an altitude of 1000m it would show a higher value (if no air has leaked) by 1~1.5 PSI. Hence this should be built in when you top up your tyre pressure at higher altitudes - make sure they set a higher value on the machines than what you maintain at sea level

[Thad E Ginathom]

Thank you for your expertise and explanations!

I'm unlikely to be in the market for the kind of cars that have low-sidewall tyres. Even if I were to be, aesthetically, I dislike them, and they come with higher risk to alloy wheels for those who like to park close to a kerb. And that before even considering the tyre characteristics.

I have never really thought about about RFT. I don't think I want to have to!