[honeybee]

I suppose the extra tyres on the rear axle of heavy vehicles are there to carry the heavy loads these vehicles usually have, not as a backup solution. Though it's an interesting idea it is definitely not practical when regular visual inspection and correct tyre pressures would keep your tyres healthy (even if they were tube type), and with tubeless tyres the tyre bursts would really become a thing of the past. To quote from personal experience, I have been driving on the expressway for about six months with a nail lodged in the rear left tyre. It being a tubeless tyre, I never even noticed the foreign body lodged inside. It was foolish on my part to not have inspected the tyres before I started noticing the air pressure loss, but the point here is even with the nail in its body, the tyre held up extremely well under expressway speeds.

Here's a link to an article which gives steps to undertake if you do face a tyre burst:

The basics of Tyre Burst / Blow Out | NowPublic News Coverage

A similar article has been published in a magazine "Which Car". Most of the advice is on similar lines, except WhatCar also suggests if you have any passenger with you, ask him to stand a little distance behind your vehicle and warn the oncoming traffic of the hazard. This not only ensures safety of all the parties, but also keeps the passenger from distracting you while you change the flat. Spot on!

Going at speeds of 80kmph, I had a left front tyre puncture on the expressway. It was a tube-type tyre. I was able to control the vehicle, slow down and gradually pull over to the left shoulder without any damage.

[mooza]

[quote=vasanthn21;1856871]
You need to know the "cause" of accident, before giving a solution
[quote]

Yes Vasanth, I fully agree it is better to know the cause, to prevent the problem from occuring. But this solution is, assuming that the worst happens, how to have a back up. It does not advocate against eliminating the causes.
And, the Tweel was what I was indirectly referring to (as airless tyres), in the first few words of my original post

Originally Posted by honeybee

Here's a link to an article which gives steps to undertake if you do face a tyre burst

Wow, honeybee, that's a great article on the best way to control the consequences ! It is worth implementing, when faced with the situation.


But, now when I think of it, the added outboard wheels that I am suggesting will also prevent people from getting stranded in the case of an ordinary puncture as well, while on their way to work, or on the highway. At least, they can limp their vehicles forward (to their destination itself if it is nearby), without causing traffic problems and mental agony. Even though changing a wheel can be done in 15 minutes, whenever I have seen my tyre flat, my first reaction is misery !

Vasanth, I think the differential is designed for handling tyres rotating at different speeds, so should not be a problem. But the steering part, yes, with a different toe out setting needed for the outer wheels, is a bit tricky, But, since the outboard wheel is very close to the main wheel, limping forward and slow turns should not be a problem, in my opinion.

[vasanthn21]

Originally Posted by honeybee

Here's a link to an article which gives steps to undertake if you do face a tyre burst:

The basics of Tyre Burst / Blow Out | NowPublic News Coverage

A very nice article indeed Honeybee.


Mooza, see my comments in bold below.

Originally Posted by mooza

But, now when I think of it, the added outboard wheels that I am suggesting will also prevent people from getting stranded in the case of an ordinary puncture as well, while on their way to work, or on the highway. At least, they can limp their vehicles forward (to their destination itself if it is nearby), without causing traffic problems and mental agony. Even though changing a wheel can be done in 15 minutes, whenever I have seen my tyre flat, my first reaction is misery !

The idea of the double tyres was to avoid accidents (may be seriuos) in case of a tyre burst, that justifies the cost of your product, not a puncture. You can always limp back to work with tubeless tyres too.

Vasanth, I think the differential is designed for handling tyres rotating at different speeds, so should not be a problem. But the steering part, yes, with a different toe out setting needed for the outer wheels, is a bit tricky, But, since the outboard wheel is very close to the main wheel, limping forward and slow turns should not be a problem, in my opinion.

Yes, a differential is designed for enabling tyres to rotate at different speeds, but if the one tyre is smaller than the other, they will obviously rotate at different speeds (as they should while taking a turn), see my point?
P.S: My engineering project was graphic simulation of differential movement

[honeybee]

Originally Posted by mooza

But, now when I think of it, the added outboard wheels that I am suggesting will also prevent people from getting stranded in the case of an ordinary puncture as well, while on their way to work, or on the highway. At least, they can limp their vehicles forward (to their destination itself if it is nearby), without causing traffic problems and mental agony. Even though changing a wheel can be done in 15 minutes, whenever I have seen my tyre flat, my first reaction is misery !

A few years back, there was this feature on the television in which some guy was shown with his automobile. It was a longish sort of car, modified to have a toilet inside, lots of other creature comforts (when AC in cars was a rarity in India). Anyways the relevant point here is this particular car had a system to use a backup wheel/tyre in case any of the running tyres lost pressure. And the owner/modifier demonstrated a tyre change (with the vehicle moving), by lowering the backup wheel, walking onto the footboard to the punctured tyre, get the wheel/tyre off and return back into the car.

Though the idea of adding another tyre or more to the existing set of four is innovative, it's hardly practical, considering the cost of its implementation. Specially in today's precision-engineered vehicles, adding an extra pair of wheels would require a complete overhaul of the vehicle dynamics. And all this cost/time/trouble to help you with a puncture?? Just use tubeless!

[mooza]

Originally Posted by vasanthn21

mooza, see my comments in bold

Yes, regarding the differential aspect, maybe what you are trying to say is that 2 different sized wheels will be trying to run from the same differential pinion, creating a strain on the drive shaft. Have I interpreted right?
But, after the burst, I am assuming that the inboard / burst wheel would have reduced in size and the vehicle would be running only on the outboard wheel. Maybe this assumption of mine is wrong, if the deflated tyre does not fully clear the road .

Coming back to tubeless tyres, let me ask just one question to all.

If tubeless tyres were so reliable, then why are tyre biggies like Michelin investing so much time and money in developing airless tyres ?

Obviously, to go a step further in assuring safety.

And I feel, if the airless tyres do see commercial production, they might be quite pricey too, if not pricier than the option of incorporation of standby tyres. If the end result can be achieved by other means as well, why not explore the other avenues, to give them a run for the money ? Instead of sitting back and waiting for technology to be delivered to us, our companies here in India too could try to do some R&D on this and come out with a quicker and cheaper solution for a safer drive.

Well, it is just an idea proposed. Better ideas may come through as well. Implementation, of course, needs a lot of effort

[vasanthn21]

My comments in bold below:

Originally Posted by mooza

Yes, regarding the differential aspect, maybe what you are trying to say is that 2 different sized wheels will be trying to run from the same differential pinion, creating a strain on the drive shaft. Have I interpreted right?

Yes

But, after the burst, I am assuming that the inboard / burst wheel would have reduced in size and the vehicle would be running only on the outboard wheel. Maybe this assumption of mine is wrong, if the deflated tyre does not fully clear the road .

Are you also assuming that on both sides (Right and left), the tyres would burst and would be running on outward (smaller) wheels?

Coming back to tubeless tyres, let me ask just one question to all.

If tubeless tyres were so reliable, then why are tyre biggies like Michelin investing so much time and money in developing airless tyres ?

Obviously, to go a step further in assuring safety.

The fact that Michelin is investing money in developing airless tyres does not mean tubeless tyres are not reliable, as you said to go a step ahead in safety. As with any other technology. For example: if companies are investing on engine research, it does not mean current generation engines are worthless, it can be improved.

And I feel, if the airless tyres do see commercial production, they might be quite pricey too, if not pricier than the option of incorporation of standby tyres. If the end result can be achieved by other means as well, why not explore the other avenues, to give them a run for the money ? Instead of sitting back and waiting for technology to be delivered to us, our companies here in India too could try to do some R&D on this and come out with a quicker and cheaper solution for a safer drive.

Well, it is just an idea proposed. Better ideas may come through as well. Implementation, of course, needs a lot of effort

Airless tyres might be pricey initially but like any other technology, with competition and with mass production, the price will eventually come down.

I agree with you - India too could try to do some r&d, and if people like you can give a viable solution, any company would buy the rights to mass produce it, the key is, it should be commercially viable. So, keep the ideas flowing

[tantragna]

My review on our design Mr Mooza that it could be made feasible to the rear pairs, but not for the front pairs because of the following points when considered in practical applications of today's cars.

• The steering pivot has to be moved much outer to offer room for the outer wheel so it does not hinder the steering by hitting/halting at the wheel arches/well - cost of new design & replacement
• since almost of the cars of today are FWD cars, the drive axles also needs replacement to the new extension.
• Due to heavier wheel (by extra wheels suspended) the steering will be heavy to operate & also cause understeer at high speeds & thus unstable.

So with these shortfalls & to serve purpose, a cheaper, more practical & a viable solution would be by adding intelligent systems into the wheels like the big cars like BMW. Merc, Audi, etc, do. It consists of a multiple data/parameter sensors like temperature, pressure, humidity, inside the wheel (tire) which are transmitted by radio signals to a car computer which does compute the real-time values, along with the history of the readings to identify & alert risk/failure with almost 0% errors.

Maybe we have to invest in such R & D projects as they are more viable than this particular one. Infact your thoughts/idea should induce more of such 'THINKING OUT OF THE BOX', which can place us on the global arena rather than waiting & begging from other countries to deliver our necessities.

Also a good care taker of his/her car would be less prone to such incidents with a lot older vehicles, rather than 'Don't care attitude' person with any top notch car!

[mooza]

Hey, thanks to all for the encouragement on this thread. Frankly, I wasn't expecting it to go beyond a couple of posts !

@Vasanth, my brains have already been picked dry, so allow me to pick your brains now

A couple of scenarios presented below, (not for the double wheeled vehicle proposed by me, just a normal car with regular wheels) :

Case 1 : One of the rear wheels of an RWD car has partially run out of air, the driver continues to drive in a straight line, unaware. Here, the dia of the partially inflated tyre has effectively reduced a bit.

Case 2 : One of the tyres suddenly becomes flat, the driver continues to drive in a straight line for some distance, and stops. Here, obviously, the effective dia of the wheel has reduced substantially, due to the puncture.

What would be the adverse effects on the differential in each case, and how would the differential behave, in your opinion ? Also, what about additional implications, if any, while taking a turn, in each of the above cases ? If you could try to explain by using the terminologies used in the link below, it would be easy to comprehend

HowStuffWorks "Open Differentials"

[honeybee]

@Mooza, sorry to interrupt. If a rear wheel lost pressure and if you tried to turn the car at moderate to low speeds, it would be less risky than if a front wheel lost pressure. On a car with a front tyre that's lost pressure and has been driven on for quite a distance, if you decide to take a full turn, the tyre may come off the rim as well.

At high speeds my guess is even a rear tyre could come off the rim, turn or no turn.

[vasanthn21]

Originally Posted by mooza

Hey, thanks to all for the encouragement on this thread. Frankly, I wasn't expecting it to go beyond a couple of posts !

@Vasanth, my brains have already been picked dry, so allow me to pick your brains now

A couple of scenarios presented below, (not for the double wheeled vehicle proposed by me, just a normal car with regular wheels) :

Case 1 : One of the rear wheels of an RWD car has partially run out of air, the driver continues to drive in a straight line, unaware. Here, the dia of the partially inflated tyre has effectively reduced a bit.

Case 2 : One of the tyres suddenly becomes flat, the driver continues to drive in a straight line for some distance, and stops. Here, obviously, the effective dia of the wheel has reduced substantially, due to the puncture.

What would be the adverse effects on the differential in each case, and how would the differential behave, in your opinion ? Also, what about additional implications, if any, while taking a turn, in each of the above cases ? If you could try to explain by using the terminologies used in the link below, it would be easy to comprehend

HowStuffWorks "Open Differentials"

I just saw your questions now, still in the middle of a project delivery man! tough days! Will respond in couple of days (will find time in the weekend - might be working :( )

[mooza]

Originally Posted by honeybee

@Mooza, sorry to interrupt. If a rear wheel lost pressure and if you tried to turn the car at moderate to low speeds, it would be less risky than if a front wheel lost pressure. On a car with a front tyre that's lost pressure and has been driven on for quite a distance, if you decide to take a full turn, the tyre may come off the rim as well.

Yes, I fully agree, honeybee. But how would the differential behave (and would there be any adverse effect on account of the changed effective diameter of the flat wheel), is my main concern.

Since Vasanth is busy, I hope some experienced Bhpians could throw light on this

Originally Posted by tantragna

My review on our design Mr Mooza that it could be made feasible to the rear pairs, but not for the front pairs because of the following points when considered in practical applications of today's cars.
.. multiple data/parameter sensors like temperature, pressure, humidity, inside the wheel (tire) which are transmitted by radio signals to a car computer which does compute the real-time values, along with the history of the readings to identify & alert risk/failure with almost 0% errors.

Maybe we have to invest in such R & D projects as they are more viable than this particular one. Infact your thoughts/idea should induce more of such 'THINKING OUT OF THE BOX', which can place us on the global arena rather than waiting & begging from other countries to deliver our necessities.

Thanks Tantragna, for your feedback ! Very valid points indeed. The axle might have to be strengthened a bit more since the bending moments would be more on account of the increased distance of the outer wheels. But regarding the steering effort aspect, well, with power steerings, should be OK I think, though I am not yet too sure.

Interesting ideas regarding the sensors. However, when a tyre hits a sharp stone, for example, and bursts, it would be safe to have a standby tyre take over instantly.

Originally Posted by vasanthn21

I just saw your questions now, still in the middle of a project delivery man! tough days! Will respond in couple of days (will find time in the weekend - might be working :( )

Hey, chill, Vasanth, please finish your work, it's important, buddy !

Regards

[honeybee]

Originally Posted by mooza

Yes, I fully agree, honeybee. But how would the differential behave (and would there be any adverse effect on account of the changed effective diameter of the flat wheel), is my main concern.

What happens when one of the wheels goes through a pothole, or over a stone? I guess the differential would be alright even if a tyre went flat. A flat tyre would cause the driveshaft to have vertical movement as well. As long as the car doesn't drive at high speeds for prolonged periods, no adverse effect on the differential.

But I am no expert.

[mooza]

Mod Note : GTO's Tyre Burst Article has been uploaded at this link. Please continue the discussion on the new thread.

A horrific mishap on NH4 recently, due to tyre burst.

Mangalorean.Com- Serving Mangaloreans Around The World!

RIP to all the deceased.

I wonder why there isn't any technology being implemented at the earliest in our modern day vehicles to avoid these incidents