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i had a blow out on my rear axle yesterday (my second flat tyre in one morning ) and that is the first i have ever had while actually moving. my concern is the fact that i heard the strange noise of my alloy running at 40MPH but i didnt notice the reason until i stopped to investigate. why didnt i feel anything either with the puncture itself or the difference in handling (straight road)

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Richie

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possibly because your car? van? is front engined/drive and all the weight & control is at the front and the rear is just a trolly wheel.

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“It has never been the rule in this country – I hope it never will be - that suspected criminal offences must automatically be the subject of prosecution” He added that there should be a prosecution: “wherever it appears that the offence or the circumstances of its commission is or are of such a character that a prosecution in respect thereof is required in the public interest”
This approach has been endorsed by Attorney General ever since 1951. CPS Code

I can own up to being terrible at detecting flat tyres, and low profiles definitely don't help. New car is apparently going to tell me.

I must admit , I have a thing about flats (probably cos I've had more than my share of them over the years (two in three days once) so I tend to jump out and check my tyres at the sound of the slightest rumble....but I'm often wrong ....

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.

was it in your car or truck? It is probably a good reflection in the quality of your tyre, that even deflated it will keep you on the road. I had a flat on the potato harvester on thursday, I had only just put it into work and was not upto "speed" when it went flat all of a sudden, it was wobbling all over the place. Speed? 1.7kph

Cars with run flat have a sensor don't they?

mitsubishi galant GDi. its a 2.4 petrol front wheel drive 4 door saloon running on 205/60/15s.
the weight at the back would have been minimal. 1/4 of a tank of petrol, the boot was pretty much empty since i knew i needed access to the spare before i went to sort the first tyre out.

sorry, there is a story of woe with this one. i got back at 7am from a night shift to find a flat tyre, front nearside. the second one was on my way back from getting the first one fixed! then to add insult to the day, after all this was done i did another job which involved bringing a whole trailerload of bloody tyres up from warrington

this is the first time i have had a blow out and it was at 40MPH, well it was when i noticed the noise which would have been 1/2 to 3/4 of a mile into the 40 limit

the other tyre was deflated when i bought the car and they resealed it before i picked it up. it has been fine since until it decided to deflate overnight

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Richie

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It can be harder to spot than one might think on well-designed modern cars. That coupled with the comparative rarity of the event, means that most drivers won't be constantly looking out for it. Also, there are blow-outs and "sudden deflations". A tyre loosing all it's pressure in a second or two feels quite different to a true "blowout", where it explodes. I've never suffered the latter but have had a couple of the former.

Some years ago, my boss and I were on the way to a meeting a long distance away. We were in his big Merc estate and taking turns to drive. He must have driven for 100 miles or so, complaining about the handling. The pair of us discussed the possibilities at length - tracking, worn dampers / suspension bushes, etc...

The vehicle didn't feel particuarly terrible to me from the passenger seat, to be honest, but I've never been a big fan of big Mercs anyway!

We then swapped over and I started driving. I really noticed it then! The car felt AWFUL. Very pronounced torque steer! It was only when I pulled in at the next services that I bothered looking at the tyres - one rear tyre only had 10PSI in it!

Lesson learned!

My Clio's tyres can get down to about 5 psi before there is any deformation. Scary.

i assume you mean static... ?
i've followed cars that look fine stopped at the lights.... come the first roundabout or corner i'm amazed they havent noticed !

Yep, static. But it has very strong sidewalls on the specific tyres that I am instructed to use.

Hmm that's given me an idea. Little RPM dials for each wheel derived from the ABS sensors. Could be interesting.

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Andrew.

What they actually do is a system called TPMS which is a pressure sensor somewhere inside the wheel.

You can get retrofit ones of varying degrees of quality. The nastiest of which replace the valve cap with something that holds the valve permanantly open allowing a pressure reading to take place, others replace the entire valve stem and thus have to have a (thankfully cheap) part of them replaced at each tyre change.

You then either get warning lights or a little gadget that can display your tyre pressures in realtime.

Don't some vehicles monitor tyre pressure loss on one wheel by looking at the 4 ABS wheel speed signals and comparing them to see if one is consistently lower than the other three?

Just a quickie...

I remember my friend had a blow-out on a motorway in his, then, Nissan 300ZX. He said he only noticed "a strange noise" and stopped on the hard shoulder thinking maybe he'd picked up a stone or something only to find it was completely flat!

The reason he didn't feel it through the steering wheel was because of modern tyre technology but also, (which no-one has mentioned yet), when you have good PAS it isolates you from any such condition.

Not a good thing perhaps but I think his car wasn't fitted with sensors to warn you of low tyre pressure. (I'm going back a long time).

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

From a Focus RS forum:

There are two main types of tyre pressure monitoring systems:

- Rotational computation using the abs system sensors
- pressure transducers in each tyre

I have one of each type on my cars.

The abs sensor type almost never gives a false reading and is associated with run-flat tyres. The other type is very often giving false warnings due to RF interference between the sensors and the control unit. The sensors are powered by the rotation of the wheels.

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Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.