[KuvamBansal]

Originally Posted by RubberGuru1113

]

You can go through BHPians’ comments and posts here to get some feedback

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.

[Cresterk]

Very surprised to see that Madhu's charges extra and that too an atrocious 4.5k for the usual installation and alignment when you buy brand new tyres from them. The authorised michelin dealer near me did it all for free even after a hefty discount on a complete set of primacy 4S and even threw in a Michelin bag

Granted this was 2 years ago so the tyre market might have changed drastically since then.

[absingh911]

I recently got a set of 4 Goodyear tyres for my city runabout in Gurgaon and price quoted was exactly the same as that of Amazon. There were no charges for installation, balancing or alignment. This was all included. Tyres were one month old.

I was having a chat with the dealer on the same topic on why should I not get from Amazon and his point of view was just service. He would not just sell me tyres but install + balance + align. He was also happy to guide me to various brands based on my usage pattern and asked to not even get air filled up anywhere but go to him once a month to get a so called "checkup" where he would be happy to look at the tyres as well as top up nitrogen, if needed. While none of these are necessary, I think I agree with him. Also, the fact that you can see the tyres before you buy is a bonus. The spare tyre conundrum would not have happened had this been offline.

[vsrivatsa]

For people interested in buying tires on Amazon - I strongly recommend also going thru this thread > (Review: Buying Tyres on Amazon.in)

And also this video:

Buying Tyres on Amazon India

[chandrda]

Originally Posted by irdevanand

Tyres will be one of the last items i would order online. I want to see the tyre, check the date, then get it fixed on my car right in front of me.

Even I had the same believe. But last week I bought 4 Conti UC6 205/60 R16 online from tyremarket.com

The price quoted at shop was around 9600-9800 per tire and the online price was 7700 per tire in Amazon and 7990 per tire at Tyremarket.

Amazon seller was lethargic in providing the manufactured month/year, but where as tyremarket was sharp in providing information. The tires were shipped to a local tire shop next day and I was able to check the tires in detail before it was fitted on my car. Everything went butter smooth

I think more then the fear of shopping online, we the enthusiast will miss the thrill and excitement of shopping for the tires for our beloved cars. May be that's the reason why we are reluctant to buy tires online

Regards

[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.

[Sen]

Originally Posted by RubberGuru1113

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.

Thank you for your detailed answer on this topic! I have TPMS installed (one of the first things I got, I'm extremely anxious about tyre bursts, they happen at the worst time with disastrous consequences, which I wanted to avoid at all costs.

I run pressures slightly on the higher side at approx. 34-35 PSI on both ends (recommended is 32 for the front and 29 or so for the back), glad to hear that it's a good practice to do so.

[ritedhawan]

Two years ago during Covid. I was looking for OEM specifications tires for my car on Amazon but couldn't find it there. I wanted Bridgestone ones for my car and what they had was from a different manufacturer for the same specs. Then I checked tyremarket.com, they had plethora of choices when it came to manufacturers of the tires for the same specs. I placed the order for four tires for my car , the website at that time didn't ask for setting up an account with them(I considered it a good thing, as its a one time buy and who knows may not have to come back to that website again). Selected the Bridgestone tires and placed an order, all tires arrived at doorstep after a considerable time. They were stacked up at home for a month before I took it to our preferred wheel alignment and balancing shop to get them installed in my car.

[OffRoadFun]

Originally Posted by PapaBravo

I do have one concern regarding your purchase. As far as I know, this tyre is 'H' speed rated which is 210 kmph. What is the stock seed rating recommended for Q5. My X1 recommends a 'V' speed rated tyre which is 240kmph.

Cheers,
Pawan

Just out of curiosity, checked the stock tires of BMW X3 xdrive 20d (190HP) today which was parked next to my Q5 today. It had W rated tire which has 168MPH (270kmph) rating whereas the max speed (not governor limited) for the same is 210kmph. I understand, some buffer might be a good idea but feel V-rating should have been sufficient.

Also checked out of curiosity the stock tire rating of another BMW X5 40i parked two spots away from mine, the tires were rated Y (186 MPH! = 297kmph). That's an overkill except may be if one drives on Autobahn.

Originally Posted by RubberGuru1113

That’s a sharp eye for detail that you have, but let me put your mind at ease - I’m an industry insider. All brands test their products to fulfil a speed rating that is a step above what is printed on the sidewall. So going down by 1 step - V to H, or H to T - is not an issue.

Thanks. That's very useful information. From what I read, a higher speed rated tire (say V-rated) will NOT behave better than lower rated tire (say H rated) at any speeds under the range of speed mandated for lower rated tire. And given the additional info you provided, I see no reason to go over H-rated for my Q5 though max speed for mine is around 225kmph.

[KuvamBansal]

Originally Posted by RubberGuru1113

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.

.

Thanks a lot for such a detailed answer. Really appreciate your time and effort in enlightening us.

[RubberGuru1113]

Originally Posted by OffRoadFun

Just out of curiosity, checked the stock tires of BMW X3 xdrive 20d (190HP) today which was parked next to my Q5 today. It had W rated tire which has 168MPH (270kmph) rating whereas the max speed (not governor limited) for the same is 210kmph. I understand, some buffer might be a good idea but feel V-rating should have been sufficient.

Also checked out of curiosity the stock tire rating of another BMW X5 40i parked two spots away from mine, the tires were rated Y (186 MPH! = 297kmph). That's an overkill except may be if one drives on Autobahn.

One more factor (that I didn't mention in my previous post about speed ratings) is Product Placement, which is followed by most global tyre manufacturers - especially in Europe where like you rightly said, insane speeds are possible, and the customer is also aware of speed ratings. So going back to the example of Michelin, the Pilot Sport product line would have a "W" or a "Y" speed rating, indicating that it's a performance tyre, whereas the Primacy series would have only "H" or V".

While the vehicle or the road conditions may not really require a tyre that can do 270 to 300 kmph, the tyre manufacturer will label the speed rating as per their product placement.

[Jeroen]

Originally Posted by RubberGuru1113

One more factor (that I didn't mention in my previous post about speed ratings) is Product Placement, which is followed by most global tyre manufacturers - especially in Europe where like you rightly said, insane speeds are possible, and the customer is also aware of speed ratings. So going back to the example of Michelin, the Pilot Sport product line would have a "W" or a "Y" speed rating, indicating that it's a performance tyre, whereas the Primacy series would have only "H" or V".
.

Here is something I found out when we moved from the USA to India. I send my Jaguar back to my home country the Netherlands. Just before it shipped I had four new Michelin Pilot Sports fitted because they were so much cheaper in the USA then in the Netherlands.

Unfortunately, one of the tires got badly damaged during one of the first times I drove my Jaguar in the Netherlands. So I went to a quick fitter. He had what was supposed to be the exact same Michelin Pilot Sport, but they had a very different thread! After some calls, we found out that Michelin has difference across the same product depending in what region the tyre is sold! Don’t understand why, but there you are.

Not sure about India, but in some countries it is mandatory to have the speed ratings of your tyres in line with the car maximum speed. If not for legal reason at least for insurance reasons. Remarkably, this applies to some countries with relative low maximum legal speeds, say 100 km/h.

Under some legal regime snow and winter tires are allowed to be of a lower class.

I would always go with what the car manufacturer recommends. With a lower speed rating, all characteristics of the tyre change. High speed ratings also means the tyre will be able to handle high torque (both from engine as well as cornering and general performance).

Skimping on tyres is simply not worth it I find.


Jeroen

[OffRoadFun]

Originally Posted by Jeroen

Not sure about India, but in some countries it is mandatory to have the speed ratings of your tyres in line with the car maximum speed. If not for legal reason at least for insurance reasons. Remarkably, this applies to some countries with relative low maximum legal speeds, say 100 km/h.

I would always go with what the car manufacturer recommends. With a lower speed rating, all characteristics of the tyre change. High speed ratings also means the tyre will be able to handle high torque (both from engine as well as cornering and general performance).

Skimping on tyres is simply not worth it I find.


Jeroen

Yes, in some European countries, insurance claims can be declined if the tire is not according to product rating.

Regarding characteristics of tyre changing from say V to H, at speeds mandated for H, based on my reading, I believe it is not true. The rating means the maximum speed a tire can attain without suffering damage. Not more than that. In fact, for higher rated tires, the structure could be harder resulting in harsher ride with no tangible benefit as the higher speeds it is rated for are almost never attained in a country like India. For a sports cars, may be they matter on a race track. For a German crossover in India, I would say an overkill, with no tangible benefit.

Tidbit: Original "H" rated tires were not so long back were called so because they were meant for High Speeds, before the advent of V and W rated ones.

[RubberGuru1113]

Originally Posted by Jeroen

. So I went to a quick fitter. He had what was supposed to be the exact same Michelin Pilot Sport, but they had a very different thread! After some calls, we found out that Michelin has difference across the same product depending in what region the tyre is sold! Don’t understand why, but there you are.

The US has very strict product recall laws…tyre manufacturers usually have different SKUs - pattern and construction - for the US market compared to India/Europe.

For instance, it’s normal to find Single Ply polyester or rayon construction (it is mentioned on the sidewall as tread and sidewall plies) even for W and Y rated tyres in Europe. Whereas in the USA, even light vehicles have a 2 ply construction. In fact, some tyres for pickup trucks even have 3 plies - this is how safe tyre manufacturers play in the US. It is for this reason that (a) The latest versions of tyres are usually launched in other markets first before a US launch and (b) There are some design and construction changes in US market SKUs compared to European ones.

Originally Posted by OffRoadFun

Regarding characteristics of tyre changing from say V to H, at speeds mandated for H, based on my reading, I believe it is not true. The rating means the maximum speed a tire can attain without suffering damage. Not more than that. In fact, for higher rated tires, the structure could be harder resulting in harsher ride with no tangible benefit as the higher speeds it is rated for are almost never attained in a country like India. For a sports cars, may be they matter on a race track. For a German crossover in India, I would say an overkill, with no tangible benefit.

Tidbit: Original "H" rated tires were not so long back were called so because they were meant for High Speeds, before the advent of V and W rated ones.

OffRoadFun is right. Basically to pass the requirement of a “V” speed rating (240 kmph), the tyre is run on an endurance tester for the following duration:-

0-200 kmph - 10 minutes
200 kmph - 10 minutes
210 kmph - 10 minutes
220 kmph - 10 minutes
230 kmph - 20 minutes

This is specified by the ECE R30 European regulation - which is available in public domain. I’m attaching the document here, but here is the screenshot of the relevant clause :-



The whole document for anyone who is interested:-

r030r3e.pdf

Basically the test ends when the tyre completes 20 minutes at max speed minus 10kmph (for a 1.7m drum test rig), and if the tyre is undamaged, it passes the test. But like I said, in reality, all tyre manufacturers continue increasing the speed by 10 kmph at 10 minute intervals till the tyre bursts, and this usually happens at least 20-30 kmph above the prescribed maximum speed; and all tyre manufacturers have internal standards which are far more stringent than the regulatory requirement.

[OffRoadFun]

Originally Posted by RubberGuru1113

T




Basically the test ends when the tyre completes 20 minutes at max speed minus 10kmph (for a 1.7m drum test rig), and if the tyre is undamaged, it passes the test. But like I said, in reality, all tyre manufacturers continue increasing the speed by 10 kmph at 10 minute intervals till the tyre bursts, and this usually happens at least 20-30 kmph above the prescribed maximum speed; and all tyre manufacturers have internal standards which are far more stringent than the regulatory requirement.

If it is done in a room at 30 degC, how is the physical stress due to loading modeled? Is the car on a conveyer belt kind of thing so that effectively car does not move? In that condition still, is it close to real life load/stress on the tire. Just curious.