Cold weather affecting tyres?

[gmaster]

Over the last week or so been having a few issue's with handling etc, ive played about with tyre pressure's but still the same! (running 30psi allround) I have verdistein ultrac tryes on the front and fairly new Hankook evo's on the rear, the front tyres seem to have little feel and low grip levels recently to the point that i feel very nervous of driving it to hard!!!!

Now im thinking it could been down to the cold weather, was out last night and it was 3c and i know these tryes dont perform to well in the cold, but they still feel the same at about 10-12c outside temp?

One thing i did notice to is they seem to be rock hard! in cold weather with very little give and very little feel and i get that sort of light floaty feeling from the front unsure of what the wheels are doing.

It seems worse since i fitted new rear tyres, im thinking about swapping the wheels over from back to front and trying the Hankook's on the front to see if this improves the sitution. Any thought or ideas? Thanks.

[Anthony 1]

I never like to mix brands of tyre, not even different tyres from the same manufacture! Cars do not generally handle well with worn tyres, particularly with different wear rates or patterns. Tyres age as they ware down, they lose compliance at he tread and their coefficient of friction is reduced. Tyres can cook with repeated high speeds and loadings, they then go off, so that they have less grip. Tyre pressures should be within manufacturers tolerances, it is a legal requirement and also the car manufacturers have spent a lot of time optimizing them, the range for adjustments is usually fairly comprehensive with wide allowances.

As the weather tends towards 0 deg C most treads harden a little and loose ultimate grip, they do not perform so well. At this time of year winter tyres will behave much better, having compounds that remain sticky at low temperatures and with tread designed for better clearance of water and slush as well a grip on snow and ice. I believe that Winter Tyres should be a mandatory legal requirement during the winter months in GB.

Edited 12 December, 2009 by Anthony 1

[gmaster]

Thanks mate im well aware of all of the above. I agree same make of tryes all round is best, but never had a problem before with running same on both axles. Tyres pressure are set at manufacturers spec on the front and 1psi down on the rear if im correct. 30psi front/ 31psi rear. Yeah winter tryes would be a good idea in my opinion too defo would help in the colder spells.

[Guest musky]

Can't say I've ever noticed a big change caused by temperature other than by pressure loss. Also don't find that I need special "winter" tyres here in the wilds of norfolk - I guess 4 wheel drive helps though

[Anthony 1]

Well their is a difference with friction as the temperature drops below 4 deg C. Winter tyres are not just about maintaing way or pulling away they are a contribution to safety. A 4 wheel drive vehicle is just as likely to slide of the road as any-other car or crash in snow or icey conditions. Their is an argument that they are more likely to slide off.

[Jim H]

I depends on the tyre, certainly Goodyear F1 GSD3 don't work when it is cold. Most tyre manufactures normally make summer tyres work very well down until 7°C. Anything below that all-season or winter tyres work better. 7° is the cross over point with these tyres.

[gmaster]

Been out driving today and im not sure it's 100% just down to the tyres, when i accelerate hard it feels like the front of the car is moving slighty left to right continuously? Also when driving in a straight line the car seems to wander again the feeling of going from left to right, maybe a bush? Though all front wishbone bushes have been replaced with superpro ones, could it be the rear bushes? then again at the mot said they were fine.

Could the rear wheels being out of balance affect the car?, i would like to get them checked again since the new tyres where fitted.

Going slighty of topic but sticking with tyres anyone read this months redline magazine? They have a tyre pressure test, where they test a renaultsport twingo with different tyre pressure's from as little as 25psi to 55psi! Stock is 35psi allround, they had the best results with lower front pressure's running 25psi 10 down on stock!! and 35psi in the rear stock psi. The car had greater grip on the front with lower front pressure's and was more nimble, interesting stuff but 10psi down on stock!!! seems a lot to me.

[Anthony 1]

Lowering the tyre pressure might temporarily increase grip because of the greater stiction provided with more rubber on the road. Over any distance this would be most likely to decrease as the tyres overheat due to too much flex. By increasing the front friction and traction the car then becomes rear end happy in that instead of the front breaking away first as most modern cars are designed to do for safety reasons, the rear tends to instead, creating faster turn in. This is likely though to make the handling indecisive as the tyres heat up, the fronts at a reduced pressure will do so first. Over a short distance the results may be encouraging but ultimately the handling and grip will become reduced and the tyres could become overcooked and damaged forever and will from then on have reduced frictional properties because of hardening.

The other thing that will be happening with reduced front tyre pressure is that the front castor angle will be reduced. This will make the car steer faster at the expense of stability because their will be less self centering.

Overall I would not run a car in this way other than on a track. With off road vehicles one might reduce tyre pressures dramatically for additional grip and floatation in boggy or even slippery ground. On the road however, it is illegal. In the event of a serious accident the police will check over the vehicle and note such things as tyre pressures. The balance of blame could swing against someone with low tyre pressures following such an accident, a prosecution would most certainly follow.

[Guest musky]

Well their is a difference with friction as the temperature drops below 4 deg C. Winter tyres are not just about maintaing way or pulling away they are a contribution to safety. A 4 wheel drive vehicle is just as likely to slide of the road as any-other car or crash in snow or icey conditions. Their is an argument that they are more likely to slide off.

I think that water or ice would make way more difference than the temperature and doubt whether there is much difference at normal winter temperatures in this country. What is the argument that 4wd are more likely to skid? That would seem to go against common sense and my personal experience. The weather in norfolk does really justify the need for winter tyres which presumably are not so good in reasonable weather, maybe if I lived in Scotland up a mountain, but not here.

From the sound of it I think there is something wrong with his steering/suspension rather than a very marginal difference in the tyres.

[Anthony 1]

Of course water and ice on the road make considerable differences in the amount of grip that a tyre might have on the road. Temperature does affect the frictional qualities of tyres. Tyres have preferred operating temperatures, the extreme of this is with racing tyres that have to be brought up to quite high temperatures to perform at their best. Normal road or summer even all season tyres are designed with an idea operating temperatures. Tyre manufacturers themselves state that normal road tyres begin to significantly lose friction at temperatures below 4 degrees centigrade. Winter tyres have compounds that remain sticky at 4 deg C and to well below freezing. The compounds are much softer. One can indent the tread of winter tyres with ones finger nails.

I know that temperatures in East Angela and including Norfork can tend to be much lower than much of the rest of England with the exception of the midlands and Kent. I have lived in Cambridgeshire and know that the winter temperatures regularly drop well below freezing. The effects of the gulf stream are much reduced on the eastern seaboard of GB, temperatures are lower than here in the west.

I do not know how long or what your experiences with four wheel drive vehicles are but I can say that I have ben driving all manor of All Wheel Drive vehicles and 4x4 off road vehicles including multi axle vehicles for well over 25 years on road off road trials and competison. The only advantage that an all wheel drive vehicle has over a normal drive vehicle is traction in the front direction or in reverse. Any driven wheel on in a bend will tend to drift outward due to a corkscrew effect when under power. So a normal rear driven vehicle will oversteer and a front wheel drive vehicle understeer through a bend. one might be tempted to think that well I have a 4x4 and this will balance out. Not exactly so without differential locks a 4x4 when the going gets slippery will ultimately behave like a 2 wheel drive vehicle or should I say a one wheel drive vehicle. When a wheel spins all the power is delivered to that wheel and all other wheels with the traction will remain stationary. This spinning wheel tend to corkscrew towards the outside of the bend. With most 4x4 vehicles one can not anticipate which wheel is going to spin at any particular time so one is not prepared like in a normal 2 wheel drive vehicle for a predominance of over or understeer depending on what axle is driven. Instead when a wheels begin to spin it could be at either rend and then suddenly transfer to another axle and wheel with little warning. So one moment pronounced understeer may take place followed the very next micro second with oversteer or vice versa. Even if one then does not come to grief, having managed to control the 4x4, it may stop due to just one wheel spinning out. Many of the better 4x4 off road vehicles might have elective differential locks so one could engage those. Some of my machines, I have several one can not only engage the central differential lock but also the rear and the front differentials, then the vehicle becomes a true 4x4 driven vehicle with all axles locked their will be no differential differences between wheels, 100% traction all round, perfect! In no way, the very first bend one comes to it will not steer it will carry strait on and go off the road through the bend. To turn at least the front axe lock will need to be disengaged possibly the rear also, it should be OK with the centre locked up. Fully locked axles can act very strangely and crab, so are not especially smooth. Some 4x4 off road vehicles have instead of axle locks they have limited slip differentials. This allows some differential movement but in theory will still allow the other wheel to grip even when one wheel in that axle continues to spin. A compromise then! Well depending on what type of LSD is fitted might determine how predictable or reliable the effects might be, some types are better than others but the need to be smooth on ice or their are risks. Friction disc type LSD are the pits on ice and only slightly better on compacted snow because they can not be relied upon to lock up smoothly, instead they can suddenly lock up or unlock when least wanted. This is just a nuisance when trailing off road but can be very hazardous on a buisy public road that has iced over or has compressed snow on it.

More recently more sophisticated electronic devices are being fitted not only to all wheel drive vehicles but 4x4 vehicles also and two heel drive vehicles cab benefit as well. Some of these are exceptionally good having all sorts of safety things stuffed into their little ECU boxes ABS and so on. Some o these will allow a wheel to spin out and yet still provide traction on the others. On normal road conditions they will help correct some driver errors but they are not instantaneous no matter what he manufacturer says. The very latest Haldex 4 generation are the dogs dangly bits but even these have delay factors to consider, yes they are supposed to sense a wheel slip in 1/7 of a rotation but one only has to watch them in action to realize that they do not respond so quickly The only other LSD a mechanical type that can do very well is the Ferguson or Torson Type LSD as used by Ferguson Tractors, Jenson Interceptors and some Audi Quatros and aftermarket Quaife Differentials also in original fit.

That was some of the theory but in practice I can verify this in real life. I not only drive 4x4 and all wheel drive vehicles for pleasure but i also drive them on my property on a daily basis, I live on a farm have driven all sorts of vehicles just to get in an out of my property which is an isolated farm with little in the way of had surfaces I know how each behaves in different conditions. Ultimately I drive some farm machinery and I can say that driving in slippery conditions 4x4 vehicles can get into quite a pickle. When driving on very severe side slips in the wet vehicles that 4x4 vehicles that can disengages the front steering axle do far better that is in two wheel drive than 4. The steering axle when engaged slides down the hill and will not steer up, only in 2 wheel drive can it easily traverse or when a full time 4x4 traverses in the same way the only way it can progress it to permanently steer up hill so one can be crabbing at 30 or more degrees front up hill just to go across horizontally. You might ask what has a tractor or off rad machine driving off road got to do with a car on the road going around a bend, but it has everything to do with it because it is the same situation but at a slower pace with similar force vectors at play.

Ultimately if one has the latest electronics and Haldex 4 we can be lulled into a false sense of security. These devices are not fool prof, they allow people to drive well outside of their normal experiences. They experience less feed back from the environment and the road to what is actually happening beneath them. When the device fails or is tested beyond its permitters the likely hood is that most people all even, will be unable to cope and come to grief. When breaking, a 4x4 has no advantages at all with traction it will still slide off the road on ice nor does it have any under lateral acceleration or when experiencing side forces such as when going around a bend. All vehicles even those with 4x4 or all wheel drive are subject to the Laws of Physics.

I think that water or ice would make way more difference than the temperature and doubt whether there is much difference at normal winter temperatures in this country. What is the argument that 4wd are more likely to skid? That would seem to go against common sense and my personal experience. The weather in norfolk does really justify the need for winter tyres which presumably are not so good in reasonable weather, maybe if I lived in Scotland up a mountain, but not here.

From the sound of it I think there is something wrong with his steering/suspension rather than a very marginal difference in the tyres.

[Guest musky]

Thats me and the rally world corrected then Thanks for a very full answer, but I'll stick to, in order of grip, best first, 4wd, rwd and lastly fwd. I've driven all over the years, not off road just normal roads, on normal road tyres, and I'd rather have a car that drifts all four wheels than just the front. I must admit to a weakness for the ones that slide the back but thats what happens if you grow up on Mk1 Capri's

I still think the guy has another problem than his tyres though, especially if its a sudden change.

[Anthony 1]

4x4 gives additional grip under acceleration and under retardation when using engine braking. 4x4 does not give additional lateral grip, in fact lateral grip is compromised under power when going through a bend for the reasons that I have stated above.

Rally drivers like 4x4 cars because it allows them to put a lot of power down in slippery conditions.

Unless the 4x4 has trick electronics or has its differential locks, the majority of cross overs do not have differential locks, one can not guarantee a stable 4 wheel drive slide either because of constant transfer of power front to back, back to front side to side.

Thats me and the rally world corrected then Thanks for a very full answer, but I'll stick to, in order of grip, best first, 4wd, rwd and lastly fwd. I've driven all over the years, not off road just normal roads, on normal road tyres, and I'd rather have a car that drifts all four wheels than just the front. I must admit to a weakness for the ones that slide the back but thats what happens if you grow up on Mk1 Capri's

I still think the guy has another problem than his tyres though, especially if its a sudden change.

[gmaster]

Wow! Im now thinking its something else and not the tyres, maybe an alignment issue etc.

[AnotherGareth]

I dislike having different tyres front to rear because in the past I've found it to be the main cause of skittishness - resolved as soon I replaced tyres on one axle to match those at the other end. For mundane driving it probably doesn't matter all that much; it's not as if the tyres are being pushed all that hard. But as soon as you start to ask more of your tyres, these kinds of imbalance become much more noticeable, and sometimes to point of making you lose confidence in your car.

[Anthony 1]

All the clues are written in the first post.

Recent poor handling

Recent new rear tyre tyres. Also Dissimilar read

Worn front tyres.

Unlike some I am not Sherlock Homes, I can only go on what has been reported of course handling can be affected by lots of influences. It does seem to me however quite obviously his tyres because of the history. Their may well be other issues with his vehicle but he was not reporting bad handling until he payed around with his tyres. Why look for other problems before he has sorted the first most obvious one out.

[vRSLen]

You will need to adjust your driving style to take into account the lower ambient temps

[Guest musky]

I was hoping to get out and boot it in the snow today but as usual what was promised wasn't delivered. Watching the news we must be the laughing stock of the entire world

[gmaster]

All the clues are written in the first post.

Recent poor handling

Recent new rear tyre tyres. Also Dissimilar read

Worn front tyres.

Unlike some I am not Sherlock Homes, I can only go on what has been reported of course handling can be affected by lots of influences. It does seem to me however quite obviously his tyres because of the history. Their may well be other issues with his vehicle but he was not reporting bad handling until he payed around with his tyres. Why look for other problems before he has sorted the first most obvious one out.

? when did i mention i had worn front tyres? i dont! the verdesteins ultrac's have good tread on them. I would like to get the same tryes on the front (hankooks), so i have the same tyres all round but cant justfy spending money on tyres that dont need replacing.

Not sure what it is could be a number of things cold weather/ new rear tyres that are causing my problems but it feels very twitchy! getting it looked at next week .

[gordonium]

? when did i mention i had worn front tyres? i dont! the verdesteins ultrac's have good tread on them. I would like to get the same tryes on the front (hankooks), so i have the same tyres all round but cant justfy spending money on tyres that dont need replacing.

Not sure what it is could be a number of things cold weather/ new rear tyres that are causing my problems but it feels very twitchy! getting it looked at next week .

I have had similar experiences with the vredestien ultracs in the cold, and indeed, i have different tyres on the rear. (Falkens)

I also find the vredesteins very stiff.

Skttishness was due when accelerating of a roundabout for example, not when braking at all. (safety etc)

my answer, is i am amending my driving style to suit conditions...

[AnotherGareth]

could be a number of things cold weather/ new rear tyres that are causing my problems

I reckon it's likely to be both.

I've had the experience of a step reduction in the confidence of front end grip when I've had new tyres fitted to the rear axle that have been a different type from those on the front, but I've never had that problem when the new rear tyres were the same as on the front.

Yesterday I was out with friends on icy roads and the only car that seemed to handle the conditions with ease was the one fitted with winter tyres.

[gmaster]

I have had similar experiences with the vredestien ultracs in the cold, and indeed, i have different tyres on the rear. (Falkens)

I also find the vredesteins very stiff.

Skttishness was due when accelerating of a roundabout for example, not when braking at all. (safety etc)

my answer, is i am amending my driving style to suit conditions...

At last! someone with the same tryes, yeah i had falkens on the back before getting the hankooks. Yeah the vredesteins are very stiff in the cold glad it's not just me, i find even in warmer weather they take a while to heat up before any real good grip. Yeah same here with the driving style.

[gordonium]

At last! someone with the same tryes, yeah i had falkens on the back before getting the hankooks. Yeah the vredesteins are very stiff in the cold glad it's not just me, i find even in warmer weather they take a while to heat up before any real good grip. Yeah same here with the driving style.

Can i ask what pressure you have the vredesteins at?

i am finding it difficult to get a decent pressure.

Sometimes they are very hard (i admit they are XL, and to be expected) but then to reduce them only 1-2 they totally change.