Sideways on the m4 (Aquaplaning)
Discussion
Hi, has anyone else found it very tough to keep their car in a straight line when it's fairly wet. I've got a DB9 on Bridgestone Potenzas.
This weekend I had a wedding in London to attend. On Saturday the weather was bad but not ridiculous for our journey up the m4. I was pootling along minding my own business when all of a sudden I was sideways in the fast lane on the surface water. Very luckily and nothing to do with skill I hit nothing and ended up facing the right way in the slow lane. I slowed down to what I thought was a safe speed as the wife was quite rightly shaken but still had shaky back end a couple of times on standing water.
I've checked the tyres for tred and they are well legal, I will be changing them tomorrow though.....
Anyway I wanted to put it out there and see if anyone else has had a similar experience.
This weekend I had a wedding in London to attend. On Saturday the weather was bad but not ridiculous for our journey up the m4. I was pootling along minding my own business when all of a sudden I was sideways in the fast lane on the surface water. Very luckily and nothing to do with skill I hit nothing and ended up facing the right way in the slow lane. I slowed down to what I thought was a safe speed as the wife was quite rightly shaken but still had shaky back end a couple of times on standing water.
I've checked the tyres for tred and they are well legal, I will be changing them tomorrow though.....
Anyway I wanted to put it out there and see if anyone else has had a similar experience.
Rik Blythe said:
Hi, has anyone else found it very tough to keep their car in a straight line when it's fairly wet. I've got a DB9 on Bridgestone Potenzas.
This weekend I had a wedding in London to attend. On Saturday the weather was bad but not ridiculous for our journey up the m4. I was pootling along minding my own business when all of a sudden I was sideways in the fast lane on the surface water. Very luckily and nothing to do with skill I hit nothing and ended up facing the right way in the slow lane. I slowed down to what I thought was a safe speed as the wife was quite rightly shaken but still had shaky back end a couple of times on standing water.
I've checked the tyres for tred and they are well legal, I will be changing them tomorrow though.....
Anyway I wanted to put it out there and see if anyone else has had a similar experience.
You can aquaplane any performance car with low profile tyres if the water is deep enough and you are going fast enough. Standing water will do that. I once aquaplaned a 997.1 C2S at around 68mph over three lanes of the M11 in hidden standing water - a dip in the road. Nothing wrong with the car handling, tyres etc - just plain old physics...This weekend I had a wedding in London to attend. On Saturday the weather was bad but not ridiculous for our journey up the m4. I was pootling along minding my own business when all of a sudden I was sideways in the fast lane on the surface water. Very luckily and nothing to do with skill I hit nothing and ended up facing the right way in the slow lane. I slowed down to what I thought was a safe speed as the wife was quite rightly shaken but still had shaky back end a couple of times on standing water.
I've checked the tyres for tred and they are well legal, I will be changing them tomorrow though.....
Anyway I wanted to put it out there and see if anyone else has had a similar experience.
Rik Blythe said:
Thanks for all of your help and advice. I will get the geo and the tyres checked just for peace of mind. If that all comes back ok, I'm leaving it at home if the suns not shining.
Obviously your choice, but I think the important thing is to understand the performance envelope of the car. Standing water will aquaplane pretty much any car with performance tyres travelling at above 50mph. It's standing water that's the problem, not a wet road. My point is, if you know the road and have good visibility you should be able to make progress in the wet. But of course, a drain can overflow and then pour water over the road. Speed vs visibility is what I was taught...
One thought that occurred to me was the age of the tyres. It seems to me there are quite a few low mileage Astons with legal tread depth but tyres that are more than 5 or 6 years old. These old tyres will have deteriorating compound which will be more rigid and perhaps some instability in the carcass. Apparently the ageing is more pronounced in lower use tyres and the manufacturer recommends replacement after 5 years ( you may say they would say that!) but the info is there , tyres deteriorate and an older car on the original tyres is quite common I would guess. As I say only a thought but are the tyres of that sort of age?
woodsypedia said:
Sorry to hear that - very glad no one was injured. I have my V12V on Michelin Pilot Super Sports and the wet handling is fantastic. If it's not your geo, try another tyre type.
I'm a huge fan of Michelin PSS but I think I'm going to jump ship in January to these - http://www.tyrereviews.co.uk/Article/Michelin-Pilo...http://www.bmwblog.com/2016/09/29/michelin-announc...
Edited by divetheworld on Sunday 2nd October 21:53
I've got a C4s and in thunderstorm or cloudburst conditions I get in the slow lane tucked behind a lorry happy to let the Clios go by in the fast lane at 70 on their skinny tyres. The risks with standing water across 3 carrigeways on 305 rear tyres aren't worth the couple of minutes saved on the journey time. Some drainage maintainence on our main roads leaves a lot to be desired.
Rik Blythe said:
Thanks for all of your help and advice. I will get the geo and the tyres checked just for peace of mind. If that all comes back ok, I'm leaving it at home if the suns not shining.
Bridgestones are OK in the wet IMO. Not the worst, not the best. OK.Definitely check pressures and other settings. But at the end of the day you were driving too quickly for whatever you hit. Leaving the car at home won't prevent that in whatever else you're driving.
The M4 seems particularly prone to this sort of thing. I've seen two cars on separate days go tearing past in poor conditions and end up in the central reservation (fortunately with no one hurt). I suspect the surface may not help matters, but fundamentally people were driving too fast.
Getting a bit geeky, but there is a calculation that will provide the slowest speed at which dynamic aquaplaning can take place, which is 9 x Square root of the tyre pressure in psi. So, around 45-50mph. Please bear in mind though, that the OPs predicament indicated that all 4 tyres had entered that state at the same time, otherwise the stability control would be working against it and possibly have saved the day. Interestingly (or not), the water only needs to be about 3mm deep for this to occur.
So, if it's absolutely hammering down, it's well worth slowing down quite considerably to mitigate against this, but don't think it's going to happen every time you go out in the rain.
Anybody still awake after that?!?
So, if it's absolutely hammering down, it's well worth slowing down quite considerably to mitigate against this, but don't think it's going to happen every time you go out in the rain.
Anybody still awake after that?!?
Bincenzo said:
Getting a bit geeky, but there is a calculation that will provide the slowest speed at which dynamic aquaplaning can take place, which is 9 x Square root of the tyre pressure in psi. So, around 45-50mph. Please bear in mind though, that the OPs predicament indicated that all 4 tyres had entered that state at the same time, otherwise the stability control would be working against it and possibly have saved the day. Interestingly (or not), the water only needs to be about 3mm deep for this to occur.
So, if it's absolutely hammering down, it's well worth slowing down quite considerably to mitigate against this, but don't think it's going to happen every time you go out in the rain.
Anybody still awake after that?!?
Double maths has never been more interesting, Sir 😀👍So, if it's absolutely hammering down, it's well worth slowing down quite considerably to mitigate against this, but don't think it's going to happen every time you go out in the rain.
Anybody still awake after that?!?
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