I have never encountered a problem with this approach.
you forgot to say...'yet'
i didn't detect anyone above being boneheaded, just some good old common sense kicking in and stating that 3mm of tread is consderably more safe than 1.6mm in the wet.. which it is
there can be many reasons why you'd suddenly be grateful for some extra leeway with your grip in the wet e.g. diesel, leaves, mud, carp, that horrible black stuff they leave when the fix the road... etc..........why not give yourself some leeway
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I have never encountered a problem with this approach. you forgot to say...'yet'
The sky has never fallen on on my head, either.
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Tyres always bring out a lot of emotion in people imo.
Tread depth (again imo) is different between summer/winter.
In winter, likelihood of more water, snow, ice, mud, general poor conditions so 1.6mm can be marginal. It can also be very safe if you drive to the standard of the tyres not the car!
In summer, more likely to be hot, warm roads, better conditions then 1.6mm is more tolerable.
But if you find you are driving to a standard where you feel the grip is not good enough; then change them whatever the wear limit is?
Personally i would rather see a car with cheap (but lots of tread) tyres than a car with famous names and low tread (which happens a lot ime). My reasoning is along the lines of that even if they cant afford the fancy names they are at least paying attention to the tyres and that means there is a chance of driving standards being better too!
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The sky has never fallen on on my head either.
>>
and hopefully it won't...but you never know, literally, what's around the next corner. A damned good emergency swerve on a wet road would provide a right good trouser filling moment on marginal tyres
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Not so sure about the "cheap" full depth against "expensive" minimum depth argument - I think it more depends on the type of tyres used - some cheap are really good, others are carp - same as the expensive ones...
On my old Fabia I had Conti Ecos as standard - at one change over I was persuaded to get Michellin Ecos - they were bloomin' awful and I ended up changing them only half worn... I tend to stick with the make/type they come fitted with from new now, and it tends to only be a quid or two dearer at the most unless I was to consider fitting really cheapos....
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>>Not so sure about the "cheap" full depth against "expensive" minimum depth argument - I think it more depends on the type of tyres used - some cheap are really good, others are carp - same as the expensive ones...<<
Its your opinion, same as my opinion is mine. But I drive a lot of cars on a lot of tyres, and unless you are really driving on the limit (if so the tyre depth/type argument shouldn't even be a thought process??) then the cheap tyres are plenty good enough for the normal car/driver. As I said, if they have good treaded tyres on at least they are aware of their tyres condition, and therefore their driving awareness??. You would be amazed how many people drive around with less than 1mm (let alone 1.6mm) on thei
But cheaper tyres with plenty of tread on are less likely to cause problems stopping, slipping/skidding in wet/ice/snow, and poor adhesion at roundabouts etc. compared to well worn tyres of any brand.
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you never know literally what's around the next corner.
True.
A damned good emergency swerve on a wet road would provide a right good trouser filling moment on marginal tyres
A good explanation of why *not* to go piling around corners where you might need to do an emergency manoeuvre 'cos of something that you have left yourself no time to react to! This whatever the state of your tyres, brakes, or reactions.
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Who mentioned piling around corners in the wet? If something unexpected and unpredictable happens you are much better off in the wet with decent tyres with decent tread depth.
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Who mentioned piling around corners in the wet?
WP's message contained these words: "but you never know, literally, what's around the next corner. A damned good emergency swerve on a wet road" - if that's the case, then the speed is inappropriate, or the driver's eyes are shut.
No disrespect to WP, BTW.
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He didn't mention going too fast. The unexpected happens, except to those of us blessed with Mystic Meg-style foresight. :-)
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i didn't take it disrespectfully, thanks anyway..... and thoroughly agree with nick's points
i.e. you could be a saintly nun as a driver and still need to react quickly to someone else's mishap/failing..and in those circs i'd want the best possible chance to come out of it... marginal tyres significantly reduce that
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The front tyres of my car are less than 18 months old and have lots of tread on them. They never squeal and I tend to keep them at their hardest setting.
The rear tyres, two different makes, just carry the back end of the car and will obviously last more or less for ever. I keep them hard too. Bad for comfort but good in every other way.
Just lately in the wet I have noticed an increased tendency to spin the wheels, or one of them, not just on metal manhole covers and so on but on the gravel and earth with which the London roads are liberally strewn. But I have always liked to feel the limits of adhesion, learn where slip angles start to get serious, in any car I was driving in any weather. I thought all drivers were like that.
Once you get the feel for the way the car's behaving today in the snow/sleet/rain/sunshine, you can stay just within those limits, or of course well within them when the road situation suggests it. It's a doddle. And surprises are quite rare if you drive like that.
Edited by Lud on 20/03/2008 at 19:07
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>>just carry the back end of the car
I don't think you could be more wrong if you tried Lud.
Without providing any rear lateral grip, you could steer the front wheels as much as you like and the car would not steer. The rear tyres perform a much greater duty than merely bearing load.
It's the sudden loss of rear grip which is truly dangerous.
I suspect that for some this particular coin will never fall - but there we are!
Regarding cheap vs expensive tyres, I think the real point has been lost. OK, so cheap tyres may offer poorer levels of grip; but, every tyre fitment and pressure combination short of optimum offers sub-optimal grip by definition. What's really important is how predictable the vehicle is. So, a tyre with no tread that offers good dry grip, but awful wet grip would catch many out, because it would suddenly behave differently. A cheaper tyre will perform sub-optimally all the time, and so, will catch no-one unawares, and hence, is safe.
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Thank you very much for filling in the details, NC.
Ever since front drive cars became the norm I have been longing for a bit more of the sudden violent lethal oversteer you seem to promise me. But only one front-drive car I have owned has ever been a nice consistent oversteerer, alas!
I thought it would be more than apparent, from the rest of my post, that the rear tyres on my car provide boringly excessive amounts of lateral grip, having nothing else to do but support the back end of the car. Of course feeling out today's wet-road behaviour in a front-drive car is nearly always a matter of exploring the slip angles at the front end. Public roads are not racing circuits.
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>>having nothing else to do but support the back end of the car.
No, no no!
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No no no!
Yes yes yes! Nothing else other than supplying boringly excessive quantities of lateral grip!
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>>having nothing else to do but support the back end of the car.
Providing the vital lateral grip is the something else that the rear tyres must do.
There's a reason why every modern car is set up to fundamentally** understeer by some clear margin. There's a reason why rear brakes have expensive pressure limiting valves or load sensing valves in the hydraulic circuit, while front brakes go unfettered. The reason is that rear grip is vital for stability.
Rear end skidding of cars is a peculiar oddity. People who are otherwise sane and reasonably safety minded will desire cars which exhibit this spectacularly unsafe characteristic.
** by fundamentally, I mean in the absence of clumsy provocation. A car driven from either end (even with boringly excessive quantities of lateral grip from the rear tyres!) may be provoked into the extremes of understeer or oversteer by the (in)appropriate driver input.
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Rear end skidding of cars is a peculiar oddity. People who are otherwise sane and reasonably safety minded will desire cars which exhibit this spectacularly unsafe characteristic.
A car driven from either end (even with boringly excessive quantities of lateral grip from the rear tyres!) may be provoked into the extremes of understeer or oversteer by the (in)appropriate driver input.NC, many years ago I had a few sessions on skidpans learning how to deal with rear end slides on Cortinas and even a Wolseley 6/110, all of which proved useful in the snowy winters we used to have.
In view of your wide and scientifically based experience, do you have a recommended technique for dealing with severe front end understeer? (touring car racers, with lots of power and limited-slip diffs appear to apply more power to pull the front back into line, clearly not suitable for the average road car, so what is the best reaction - lift off or unwind lock or both?)
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In view of your wide and scientifically based experience,
Oh dear, have I said something out of turn?
do you have a recommended technique for dealing with severe front end understeer?
I'd begin by stopping whatever was going on to provoke the front end skid - letting off the throttle a bit if it's an over acceleration skid, unwinding the steering if too much has been fed in, etc, etc,...
As ever, getting out of skids is hundreds of times easier to do when speaking or writing - while the scenery is spinning past your windscrren it's a bit difficult not to just jam on the brakes!
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Oh dear.
The best way to get out of 'skids' is not to get into them. The way to avoid getting into them is to constantly explore the speeds and lateral forces at which they begin to set in, and play around and below those speeds and forces except for the occasional joyous, safe wriggle.
All this drama about 'skidding' with one end of the car or the other! Surely in reality the whole thing should be fluid and rapid with constant inputs and monitoring. Not getting into some oafish 'skid' and thinking, oo-er, how do I correct this?
I always thought that was what road driving was all about.
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snipquote for the lazy person who can't be bothered summarising the message he's replying toI'd begin by stopping whatever was going on to provoke the front end skid - letting off the throttle a bit if it's an over acceleration skid unwinding the steering if too much has been fed in etc etc ...
NC, I always read your postings with interest; having worked with automotive development engineers myself I have noted that such people usually know what they are talking about and their advice is usually worth heeding.
To deal with excess understeer (as in the case of a bend where the surface changes and/or tightens midway) backing off power and lock has been my instinctive reaction on the rare instances I have had this; last time it was a patch of wet leaves in a dip on an otherwise dry road.
Edited by Webmaster on 21/03/2008 at 12:46
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>>backing off power
This gives a couple of effects - one of which is via weight transfer to put more vertical load on the front tyres, allowing them to produce more lateral force. Although more vertical load actually reduces the effective co-efficient of friction between tyre and road, the amount of grip available does increase.
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you could be a saintly nun as a driver
You could, but I'm afraid that I am not!
and still need to react quickly to someone else's mishap/failing..
True enough - but I have found the number of unanticipated problems vanishingly small, thank goodness.
and in those circs i'd want the best possible chance to come out of it... marginal tyres significantly reduce that
That depends on circumstances. However, I'd be buying around 5/4 times the number of tyres I've historically bought.
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good emergency swerve on a wet road would provide a right good trouser filling moment on marginal tyres
or any tyres on cow poo lanes believe me. 1.6 is carp because by this point the walls MAY be failing. I know that on top class commercial 8 ply van tyres that well before that point that there is other, more significant wear in areas other than the tread.
MD
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