[dutta_d1]

Found an old article in TOI website about the Mumbai Pune Expressway and safe driving. But one part that I am finding hard to swallow is the one that says, "An experiment conducted recently by the expressway administration and highway traffic authorities revealed that the difference in time taken by a speeding car (more than 100kmph) and a normally driven car (80kmph) to reach Pune from Panvel or viceversa , was only eight-and-a-half to nine minutes."

Anybody can say if this is credible? I think the difference will be more than 8-9 minutes.

Nevertheless, it seems tyre blowout still is an issue, not withstanding the various improvements in the manufacturing process.

[mmxylorider]

Considering that the MPEW has the ghat stretch where speeds are automatically limited by the curves, gradient and lumbering truck traffic - this number seems alright.

When I've used the old NH4 instead of the MPEW, for Pune-Panvel the time taken is just 15 more minutes. Speed does not exceed 90 kmph on either road.

[anandjha]

The day this story had appeared in TOI there was another related news in Dainik Jagran. A car had suffered twin tyre bursts on Yamuna Expressway. It was not driven over 100, as the car owner claimed, and was only 3/4 months old.

A few days ago when I had gone for nitogen filling I had heard another similar news. This time it was an SUV, which had burst all its 4 tyres one after another. Again, as the tyrewalla claimed, all 4 tyres were new.

Can someone throw light on what could have gone wrong?

Could stone chips, as pointed in one of the earlier posts, implanted within treads be the reason?

[srishiva]

Concrete roads are also preferred in hot climates. They last much longer. But aren't they cooler than black asphalt ones? The friction is higher which makes it very noisy and relatively unfriendly to tyres

In India, I have seen concrete roads that are much rougher than abroad. Do they smooth-en after wear?

[Santoshbhat]

Combination of modern cars capable of very high speeds and four lane highways has meant that the average speed of vehicles running on the highway has gone up substantially.

I drive quite regularly on NH4 and rarely find passenger cars, MUVs, and SUVs moving at speeds less than 100 kph. I find many cars driving on wobbling wheels, underinflated tyres, worn out tyres etc...

A decade back driving with such tyres was not such a problem as speeds were lower. We had only two lane highways and a car with 100 bhp was considered a sports car. But today if tyres are not in top condition it can be unforgiving. My guess is about 80% of motorists driving on the highway are oblivious to the dangers of driving on highways with poorly inflated/ worn out/ damaged tyres.

My main worry is no matter how aware I am of the importance of tyre quality on highways, I am sharing the road with other drivers who are not. What happens if a car that is hurtling down from opposite direction has a tyre burst? Its that element of risk that we all take while driving I guess.

[torquecurve]

Originally Posted by dutta_d1

Found an old article in TOI website about the Mumbai Pune Expressway and safe driving. But one part that I am finding hard to swallow is the one that says, "An experiment conducted recently by the expressway administration and highway traffic authorities revealed that the difference in time taken by a speeding car (more than 100kmph) and a normally driven car (80kmph) to reach Pune from Panvel or viceversa , was only eight-and-a-half to nine minutes."

Anybody can say if this is credible? I think the difference will be more than 8-9 minutes.

Nevertheless, it seems tyre blowout still is an issue, not withstanding the various improvements in the manufacturing process.

I have given a workout below. The number is credible. I have taken average speeds. Typically you will have an average speed of 60 if you have a max speed of about 80 due to the speed restrictions on certain sections (Ghat, Amrutanjan Bridge, etc).

Distance 93 is the length of the expressway. Distance 120 approximately is including the travel to Panvel after exiting the MPEW on the Mumbai side and NH4 to MPEW on Pune side.

[tj123]

In my view it is basically a combination of good stretch of road, powerful car leading to higher speeds and tyre condition (under inflated, patched, repaired, damaged sidewall , wrong tyre rating , poor quality tyre etc). When we have all these conditions coming together then we are very likely to see tyre blowouts.

Concrete roads are generally more rough and has numerous expansion joints, these joints are not very smooth you can feel and hear them when the wheels get over them. Tyres when subjected to constant cyclic high speed shocks, any weakness in tyre condition will showup sooner than later. That's is my take on this issue.

[phamilyman]

Originally Posted by SS-Traveller

An interesting point to note, which any other Scorpio VLX owner can reconfirm and corroborate.

While cruising in a 100-110 km/h speed band on tarmac (bitumen) highways with 3 persons on board and moderate quantity of luggage, my tyres do not register a temperature above 58-60*C, even in the peak of summer (around 45-50*C in winters). On the other hand, cruising in the same speed band on a concrete highway pushes tyre temperature close to 70*C in summer.

Thanks - this is very interesting and helpful. Does the car measure this, or have you like paused mid-drive to measure it? So clearly these numbers - coupled with the immense gravel/FO on our roads, there is very high chance of FOD on Indian roads.

How does it look like at a 90 kph run (the speeds I normally cruise at). I am hoping the temp diff versus the ambient temperature to have a square relationship, thus those speeds being far safer for the tyres.

[nayaksudhir]

Originally Posted by tj123

In my view it is basically a combination of good stretch of road, powerful car leading to higher speeds and tyre condition (under inflated, patched, repaired, damaged sidewall , wrong tyre rating , poor quality tyre etc). When we have all these conditions coming together then we are very likely to see tyre blowouts.

Exactly the point. You have summed it up and articulated well. Now the idea is to find out the right values for these variables which can then become useful information. For example: Tyre pressure: xx PSI; Ideal Speed on Concrete: yy kmph to zz kmph... And so on.

Experts any?

[SS-Traveller]

Originally Posted by phamilyman

Does the car measure this, or have you like paused mid-drive to measure it?

How does it look like at a 90 kph run (the speeds I normally cruise at).

The Scorpio TPMS system displays a pressure and temperature readout of each running wheel on demand on the speedometer console.Don't need to stop/pause at all.

I am sure different cars should have different tyre temperature characteristics at different speeds, but to answer your question, at 90 km/h in summer, temperature remains ~55*C when driving on tarred roads. In fact, I don't remember the temperature crossing 60*C except when running on concrete surfaces on summer afternoons.

[Utopian]

This is really some news. I recently traveled to Agra using the highway. Maintained fairly high speed during the journey. Will be more prudent this time around.
Thanks for sharing.

[SR71A]

Most Concrete roads in India Including MPEW are Jointed reinforced concrete. The joints are given to prevent expansion transverse cracks. These joint are normally filled with Bitumen, which degrades over time and leaves fairly large gaps, which causes enormous strain on the sidewalls as high speeds. This in my opinion is the reason for many side wall failures in low profile and poorly maintained tyres.

Abroad they have perfected Continuous joint less concrete pavements.

Concrete is much harder and does not flex under vehicle load, therefore there is fraction less rubber in contact with the surface hence lesser grip. This becomes aggravated during wet conditions. The hardness also leads to more tyre wear. Concrete surface needs to be grooved to have sufficient skid resistance. The grooves retain water even in well drained surfaces leading to more chances of hydroplaning.

Asphalt surface is smoother if properly designed and laid, hence less road noise,more grip, it drains easily. Most airport runways are Asphalt, as are most race tracks and new BOT highways in India.

A slightly reduced pressure on concrete hghways should help the motorists.

Both road laying techniques have there fans, but this is my two pence on the topic.

safe motoring.

[debuda]

Originally Posted by Fiatanic

Filling up nitrogen will definitely help, the gas does not expand due to heat like air does. But it means that a guy driving without any knowledge of tread thickness/nitrogen should pull over every 25 kms, pour water over all the four tyres and rest for 10 minutes, will that help him prevent a tyre burst in the middle of highway?

There appear to be lots of myths / misconceptions regarding using Nitrogen for filling passenger car tyres. IMHO, use of Nitrogen offers negligible advantages. A detailed analysis can be read at this website.

Originally Posted by lancer_rit

I guess one needs more precautions when travelling on fast concrete expressways.
Proper tyre inflation for the load, and making sure you're not running on tyres whose rubber may have hardened (more than 6 years old or 60k km done, say) and can crack.

Given Yeti's unfortunate fatal blowout on MPEW, one cannot emphasize more on doing whatever is possible to keep car tyres in good condition. Rather change earlier, than try to extract a couple of thousand bucks more by running tyres for longer ?

Of course, one must also ensure more than legal tread depth (I would say atleast 2mm depth rather than the legal 1.6).

From information I gathered from various sources plus my own extensive driving experience in India and Europe, I can share the following :

1. There are many different technologies of building asphalt as well as concrete roads. Better technology and quality of material / workmanship lead to smoother and more durable roads. Whereas concrete is known to be more durable, asphalt usually offers more smoothness.
   
2. Tyres usually run hotter (and noisier) on concrete as compared to asphalt / bitumen. Therefore, one should drive at relatively lower speeds on concrete, especially in hot weather.
   
3. Though most modern tyres are 'speed-rated', one should not get a false sense of safety by accepting the speed rating blindly. Factors like type of road surface, ambient temp., tyre pressure, tyre temp., tyre age and tread depth all greatly affect the speed rating. For example, a brand new T-rated (190 kmph) tyre may burst at 130 kmph if it becomes overheated (due to high ambient temp. or low tyre pressure or poor alignment or high friction on rough / concrete roads). Similarly, as the tyre gets older and worn, its speed rating gets derated.

[scuderiamania]

I have very little understanding of how a tyre reacts to different surfaces under different conditions, but there is one peculiar thing that I recently noticed will on my way back from Orissa on NH-60 which is completely concretised. We had just pulled over by the side of the road when we noticed that the surface of the tyre was unusually clean. I mean as clean as they usually are when they are in the showroom! And the tyre was definitely hotter than usual. I thought it was because off the heat from the mid day sun. I guess I was wrong. PS: Our car was running on Yokohama AVS ES 100s that are about 4 years old.

[scuderiamania]

Originally Posted by dutta_d1

Found an old article in TOI website about the Mumbai Pune Expressway and safe driving. But one part that I am finding hard to swallow is the one that says, "An experiment conducted recently by the expressway administration and highway traffic authorities revealed that the difference in time taken by a speeding car (more than 100kmph) and a normally driven car (80kmph) to reach Pune from Panvel or viceversa , was only eight-and-a-half to nine minutes."

Anybody can say if this is credible? I think the difference will be more than 8-9 minutes.

Nevertheless, it seems tyre blowout still is an issue, not withstanding the various improvements in the manufacturing process.

This is something I completely agree with. I often travel with friends and family from Kolkata to Shantiniketan, a distance of a 180kms. I have seen on several occasions that friends go flying past us, sometimes in excess of a 120kmph. But my father who doesn't go beyond a 100 [but tries to keep up the momentum by not braking as much as others] covers the same distance and is never more than 10 minutes behindd the others. I strongly believe it is absolutely useless to go beyond a 110 kmph on the highways as you hardly gain time and only loose fuel. I drove on highway for the first time a couple of days back and stuck to my limit of a 110kmph and was able to keep pace with another uncle driving a jetta and pushing it to 140kmph at any oppurtunity he could get.

PS: mods, please merge my two posts. I tried to merge them but am unable to delete either of the posts!