High Or Low Tire Pressure In Snow And Ice

Is "increasing tire pressure" above the normal recommended tire pressure range?

I know of people that add air in the winter to both keep within the limits in their owner's manual and to keep the low pressure light off.

I also know of people that use low pressure to increase the surface area of the tire. After all the fatal SUV accidents in America a year or two ago (caused by low pressure) I doubt anyone in an official position in the industry would dare recommend using low pressure. When I lived in the northern US I would add air to keep pressure in the recommended range.

Back to my first question. Does "increasing tire pressure" mean that he just added air or does it actually mean that he increased the pressure for the winter?

Hey Ky, having lived in high country most of my life, good aggressive tires helped with about a 10 lb drop. Bigger tires bounce a bit anyway. Could be a benefit or not. This always depends on the terrain. Mud and snow combos, less air helps. All snow, keeping the tire pressure at recommended helps to fling snow. Also depends on how well the snow packs. The pix here is with Super Swamper's and were great for snow of just about any kind. Keeping some of the air out (10 to 15) proved to be the best set up from all of us running these types of tires. Including other brands of an aggressive nature. When it comes to ice, it seems to help but positive results is always up to the drivers abilities and always type of ice covered terrain. If it's serious, adding 1/4 square head metal screws in to the tire helped immensely. I do it on some winter tires on my motorcycle. Better than spikes I feel. But I don't haul butt on them either. For the street it was always 8 lbs or so on radials. Uh oh, showing my age! In newer cars and trucks it's always better to just do what the manufacturer recommends, if anything bad happens, then law suits will have a better chance for success. Since that's what it ends up being anyway!

If driving on hard pack snow, I would keep the recommended tire pressures. If you encounter ice, lower the pressure for better traction, but go back to regular pressure as soon as possible. When I was working in Quebec, everyone drove 60+mph. The roads were hard pack and due to the very cold temperatures (zero & below), the roads didn't freeze. It's when the temperature is just below 32° that icy conditions are the worst.

Thanks all

Thanks artsmith

What you are describing is exactly the reason I left those climate zones more than 25 years ago.

Back then we could do with our tire pressure whadeva we wanted. This is Hamburg and suburbs sort of an environment. Sometimes it was necessary to change the pressure back to normal but a service station was always around the corner. It was not to and fro work place but sometimes hours at a time of doing the traveling sales man routine, saving minutes here and there.

You would not want to go home on the autobahn and not have your tire pressure right unless you vary your speed accordingly.

The lack of service stations is a good argument against lowering the pressure and not be able to change it around, at will. I never did but then again I am a driver, who, if he would be any more passive, he would stay at home.

In the end and from my experience I would do it again. It was just that extra grip, just noticeable to a good driver.

Chris, do whatever makes you feel good. You would be too lazy to deflate your tires anyway. .

Wanna see what you are missing? I knew you would

Sorry all others _{but this is personal}. There wont be tire tracks along here in a rush.

Gotta go, Ky.

My eyes are not as good as they once were. Is that a layer of fresh snow with the shadow of a palm tree on it?

I don't understand why you want to torture me...

"afaik, there is a loss of a couple psi pressure for every 10 degree drop in the temperature. "
This can be determined exactly by the gas laws. By my calculation the pressure drop resulting from a change of temperature from 20 degrees C to 0 degrees C is from 35 psi to 32.6 psi, or 2.4 psi.

"So it is recommended in some circles to adjust the tires in autumn, increasing the pressure a little to compensate for that loss, to keep the pressure at the recommended level."
The logic is a little convoluted. Would it not be simpler to say "In both winter and summer, check the tyre pressures regularly, keeping them within the manufacturer's recommendations"?

For those living in regularly snowy conditions, the fitting of snow tyres is a more effective safety measure than playing with the pressures. The rubber in these tyres is designed to retain its flexibilty at lower temperatures, and the braking distances, even in the dry, are measurably shorter. But even for snow tyres, the manufacturers still recommend specific pressures, and they should know.

GA

GA Art. I have included a calculation that will help anyone who is trying to equate the warm tire pressure to the cold tire pressure. From such information, you can create graphs or simply use the rule of thumb of 1 psi/10 degrees C. This is the link, if anyone is interested. I live in Canada but where I live the roads are not snow covered much more than 10 percent of the time. Unless you have tire pressure monitoring and some mechanism to auto inflate/deflate the tires, I would not do much more to the tire pressure than adjust for the recommended equivalent pressure for cold weather. If you have icy and snowy roads, drive accordingly with a little more caution. Don't venture out on the snow drifted highways unless you really have to get somewhere and not in a hurry. Carry some emergency equipment for cold weather (maybe a set of chains if you expect to get stuck).

One caveat, measure your tire pressure in the cold air and not in a heated garage. Give the tires a chance to reach ambient air temperature.

I do believe that its mostly only Canada that has heated garages.......some US ones get heat from a boiler in there (or near), but in Europe, they are very few and far between.....

Often in my garage its colder than outside......winter and sommer....

......just for the record!!

No links open calculation .

any problem in link or URL?

Calculation Thanks Hajee

Kevin

Living in the great white north, this is how I understand it. Tires are designed to operate at a certain profile to be most efficient. In the summer, we check tires when cold because after running the tire heats up and the pressure rises. This pressure increase brings the tire into the most efficient profile. In the winter, there is not the same amount of heat build up due to more efficient cooling of the tire. By increasing the pressure when cold, above summer pressures, we are bringing the tire up to its most efficient profile. Yes, by dropping pressure, traction may be increased, but this can result in sidewall failure. This may not be immediately noticable, but could result in sidewall failure at a later date when the tire is most loaded, high speeds in the summer. As most winter driving is done at 90+ kmh, running under design pressure will result in excessive wear in the middle of the tread, possible damage to the sidewall, lower fuel economy and poor handling. If I need more traction, I bring in the front end and if that is still not enough, them I put on chains, front wheels first, and if necessary then the rear wheels. The times I have had to do this was to get poor fools out of the ditch. Needless to say, I was not travelling at speed.

I run four winter tires for six months a year, the rest of the time I run all- seasons. I consider all -season tires only three season tires at the best.

Ford dropped the air pressure on Explorer tires and we all know the result. If you have to drop air pressure to get added traction, get them up to proper inflation ASAP.

Yes, there are lots of ways to increase traction, but using the proper ways will be cheaper in the long run.

As stated, "modern" tires are designed to operate at a given pressure to preserve the tire profile. Raising or lowering the pressure from this value will create longer term damage to the tire. Contrary to popular belief, lowering the pressure in radial tires does not increase traction, but actually decreases it because less of the tread is in contact with the driving surface. When the tire pressure is below the operational range the tire tends to "cup", where the center of the tire tread raises above the surface and the tire rides on its edges, causing excessive wear at the edge/sidewall. This is how under-inflated tires appear, heavily worn on their edges with full tread in the middle. Old style tires, available before the radial designs became popular, did not have this characteristic and lowering the internal pressure would place more tire surface on the road. As noted in many posts here, keep the tire pressure at, or near, the manufacturers recommended level in winter or summer to maintain the proper profile and maximum tire surface contact with the road surface. One additional recommendation is to keep your tires properly aligned to maintain proper "tracking" on slippery surfaces.

Sorry to remove your OffTopic rating to add a GA.

"running under design pressure will result in excessive wear in the middle of the tread"

Please explain.

I believe this comment has been inverted. Excess pressure, on a vertical tire, will reduce tread wear, but the wear that does occur will tend to be in the middle. Too little pressure tends to increase overall tire wear. With a vertical tire (as on the rear of a solid axle car) too little pressure results in pronounced wear on both edges. With factory-recommended negative camber, and proper toe-in, tires wear on the inner edge, whether over, under or properly inflated.

It is obvious that a tire carcass can fail from too little air, especially when heavily loaded. I have had tire structural failure on name-brand radial tires always run at high pressure, so running 2-8 psi over nominal can also take its toll. It only happened to two pairs of tires, out of more than a hundred pairs of tires over 40 years. Tires do their job very well.

A good post, but fails for a GA in my eyes because although I have been driving over 40 years using the maximum allowed tyre pressure recommended by the car manufacturer for full load.

Doing this I have never had a problem with center wear using sometimes even more than your mentioned 2 to 8 PSI over nominal (whatever that is......but I assume its the normal lightly loaded tyre pressure.)

When I go on holiday with my caravan, both car and van are fully loaded, so after about 6 miles I stop and check how warm each tyre is getting, if more than my blood temperature approximately (back of hand against tyre), then a bit more pressure is pumped in till the tyres run cool......tested again in 10 miles or so (depending upon the Autobahn stopping places...)

My one blowout was on a caravan tyre that had been over heated by the previous owner at some point, the very first time I pulled it......!

Never had a blowout on any car or caravan other than that one time. (had a few nails and the like, but all were repairable, even one at well over 100MPH!)

The only negative effect is that the "springing" is a bit hard, but after a few days you don't really notice).

The plus point is fantastic braking, better more accurate steering and very very long life tyres........

I do believe that you could be correct if say the tyre pressure was doubled or worse. But as I have never tried this out, its just a strong possibility I feel......but not a known fact (at least by me!!) Maybe someone else has more experience in this area.......

Sorry to be picky about your otherwise excellent post!!

The earliest of my failures was a Vredestein performance tire decades ago... Its carcass gradually went out of round badly, but the tire still holds air, 25 years later. (the Mustang has been stored for a long time)I had been running it at between 2 and 8 psig above the sidewall printing. The sidewalls describe the pressure, cold, at which the US govt agrees that the tire will carry its maximum rated load. At less than this printed max load, pressure is more or less up to you. They had a lot of autocross, track day and fun highway curves on them. They were side-load abused, but never run soft.

It was well known back then that more pressure meant less roll-under of the tire, and thus better cornering on dry pavement. We could confirm optimum pressure for dry cornering with a 200 foot circle marked on a big piece of pavement. With a given pressure, the lap time for a steady speed at 5% slip and 10% slip is recorded. Pressure is raised by 5 psig. If lap time goes down, we step up pressure again, until we find the optimum, one end of the car at a time. Suspension characteristics and camber have an influence, but for a given radius, this technique works well. I have been holding this sort of performance set-up exercise for entry-level autocrossers for 40 years. Tires have evolved, but this process still works.

With more pressure, rolling resistance goes down and tread life goes up, but if the roads are bad, ball joints etc will have a shorter life. If the tires are cheap, the speeds low, and the suspension expensive, the optimum may be 2-4 psig above or below the pressure recommended by the automaker. If the roads are nice, and the curves are fun, then I recommend experimenting with more than the carmakers idea of 'correct'.

Fantastic, well thought out and easy to follow up!!!

My method is not so scientific, but "errs" in the same direction I feel!!!

Many thanks for one of the most interesting posts for a long time.

GA

We don't get real snow here in the UK but just to add to Tundrawolf's comment, if you watch the guys driving in rallies they tend to switch to narrow tyres when driving on snow in order to cut through & find grip. If you watch people competing off-road in snow they use wide soft tyres.

Dear Nigh,

''We don't get real snow here!!!!!'' Well if you had been media savvy over the last few days you would have seen what we do get causes real grief when it lands on you. I travel to Aberdeen regularly and there has been plenty of evidence of what that white s***** does and what chaos a lack of traction causes in the past few days.

Just be patient and you southerners will be enjoying similar fun 'ere long, so think about contact areas and low temperatures before dismissing the effects upon your overcrowded roads when trucks jacknife and car drivers get it all wrong.

In the mean time book some time on a skid pan and practise all those dwiddly bits........have fun and as Dave Allen used to say ..'' May your god go with you''

Happy motoring,

Massey.

Perhaps I should have added 'down south'. Even when we had some heavy snow last year driving was OK with suitable precautions.

GA For the best post I have seen here so far. Thanks from me personally.

What many forget with winter tyres is that the tread is partly composed of fine slits (sometimes in "zig-zag" form) that open when that part of the tyre is near or on the ground and they give that extra grip on ice and snow when needed.

Deflating a winter tyre causes some of these slits not to open correctly and the extra traction/braking effects is lost/reduced......

As some have said, a winter tyre will work better for most conditions when fully inflated, even fully inflated to the max load pressures for that vehicle.

Also pointed out by several people is the fact that if the weather warms, and/or the road is clearer for faster driving, a partially deflated tyre may overheat and explode.......many have experienced this already in their lives!! For some it was the end of their life......

As you say - it depends.

But you are surely pulling our legs when you suggest that comparison with the operation of ice skates suggests tyou want a narrow tyre?

Skates provide average pressure that exceeds 1000 psi, and the combination at the front edge of high peak pressure and sheer melts the water and makes you slide - which is not exactly what you want with you tyre. In any case, the low-speed pressure applied by a pneumatic tyre will generally be only marginally higher than the internal air pressure.

There is some possible comparison between skates and the action of studs and chains - studs and chains can cause local melting that allows them to sink into the snow - but the shape means that the studs/chains are now trying to shift the surrounding snow (or ice), which increases grip.

Returning to tyre pressure: regardles of the effect on grip, there is definitely a durability problem with standard tyres that are underinflated at low temperature, as the combination of increased flexure and reduced flexibility can initiate cracking - leading to subsequent "unexplained" blowouts in mid summer. Winter tyres are more tolerant, and there can be advantages underinflating them on thick snow - but only at temperatures within a couple of degrees of freezing.

The tyres blow because with low pressure, they overheat.

The rubber is simply "working" too hard....

If you get a piece of metal or plastic and you fold it backwards and forwards quickly, it only takes a few "folds" for it to get too hot to touch......rubber reacts the same way.....

The pressure, though low, will eventually blow the tyre apart as the rubber gets software and softer...........

Low pressure blows more tyres per year than high pressure ever does!!

Hi Andy

Just to get you and a few others away from the panic button I never suggested for young Chris to deflate his tires to a dangerous level. What I said was that I deflated them in such a way that only an experienced driver would even notice the difference.

I was not taking part in any rally back then but was doing pick ups and deliveries when I was not doing my rounds in the factory to make sure all machines were running safely and at maximum out put. (mass production of picture frames)

I do get your point about sloppy tires and the results of driving around with them. Modern tires are a bit different to the ones that were fitted than back then. You know, they had even introduced spikes back then and that was a bit of a shot in the arm.

Last time I witnessed snow was more than 30 years ago and yesterday when I watched the news. Poor bastards is all I can say

You're right Mate?

Say G'day, Ky.

I can speak from experience in dirt track racing.If the track is hard packed,you need soft tires.If the track is soft and muddy, you want hard tires.Always match hard-to-soft or vice versa.This gives maximum contact between the two surfaces.Imagine two steel balls under pressure at point of contact.Not much contact area.

Now imagine a rubber ball and a steel ball under pressure.Much more contact area and more traction.

So for powdery snow,(very cold and hard surface),soft tires (low air).For mushy wet snow, hard tires.(High air).

For sandy conditions,more surface area is better:Consider camels' footprint in sand,and a moose footprint in snow for examples.

Of course, ice is a whole different game.Nothing gets really good traction in ice.The ice skater gets traction from turning the skate sideways and pushing off.Under the blade is water,formed by the compression of the ice,which is why the skate has very little friction when in motion.

Hard tires on dry snow tends to create a water layer below,which reduces traction.

For mushy snow, you want to get below the mush to the pavement if possible.Of course, mother nature does not give us these cut and dry situations, so what I would do is adjust according to what you anticipate to encounter,but remember to adjust back to normal as soon as possible to reduce damage to sidewall due to excessive flexing. I run mine at slightly higher(2 psi) and reduce if conditions change.YMMV

#18 is basically correct.

One must consider that the conditions we face in winter are even more varied than those in warmer weather.

When there is soft slush or fresh snow, a tire is best if it cuts through to the pavement. It can do so best if it is narrow, and 'fully' inflated. If the snow is deep and fluffy, a narrow hard tire acts as a rudder, and has better directional control than any other. For getting unstuck from deepish snow, a soft tire has the same advantage it does in deep mud. Drop the pressure to get unstuck, but keep it high for safety until then. Modern cars come with wide tires, apparently to simulate dry pavement race tires. They look very cool (?) It is very counter productive to have snow tires in that aspect ratio.

A tire carcass can fail due to overheat and low pressure as easily in winter as in summer. For highway use, keep at least the automaker's recommended pressure in your tires.

I have been using studded snows all around in my winter vehicles for 15 years now. I have been an official in Manitoba Ice racing for 25 years. Small sedans and sports cars on frozen lakes.

I did drive in the great lakes area (deep snow and not much below zero C) with both snows and non-snows for decades before that. Get good tires if you have to drive in snow. Studs make a huge difference if you have a frosty road. I have found these across North America, and hitting this at night on a previously dry road is scary. Twice I have been Awakened by the driver as I snoozed in the passenger's seat, with the car beginning to yaw/ rotate on a suddenly icy highway... in MN and WA. Better to have the studs already in place. Studs in the front of a front wheel drive, and non-stud in back, is OK in the city, but very scary on a suddenly icy highway.

The stud makers got cheap about 8 years ago. You get a 12 or 13mm long stud, with only 2mm of carbide in it. When the tire and stud wear by 2mm, you have only steel left, and a steel stud wears so much more quickly than the tire, that the studs hide below the level of the tread, and become completely useless. Before you buy the studs, take a sample, and run a straight pin up from the fat end. If it has the short carbide, the pin will go almost to the top. A good carbide will fill almost the entire length. If any stud sits a little high on your new snows, ask that it be replaced free. It means the guy has not got the head in all the way. I used to stud tires at a place on Woodward Ave in Royal Oak MI, and when your hand gets tired, you do a bad job.

I have been very pleased with the skinny studded snows on everything from sports cars, to a tiny Suzuki, to my wife's Caravan. If going undersized in new snows, for narrowness, keep in mind that the tire must be adequate for the weight of the vehicle, and must not rub the (front) plastic inner wheel well because it is too tall.

It sure is fun out there in the snow. Manitoba is the only place I know of to have ice racing every year. Everyone else has missed a race-season recently due to a mild winter. Our season starts in early January, when our lakes are usually 20" deep in clear ice.

David

It would be great to have studded tyres in winter, but here they are banned for normal road usecompletely.....I do believe that most of Europe is the same.....but not completely certain of that...Probably Switzerland allows them - maybe!

They tear the tarmac up something cruel if a lot of cars use them. They were legal for a short time about 30 years or so ago......

Last Friday, the law was changed in Germany to make winter tyres a legal requirement, (before, some insurers took away your cover if you had summer tyres on in an accident! Now they can do that completely legally.....).

The good point is that it took millions of cars off the road when the snow came at the weekend!!!!!

With all due respect, this is the most non-scientific argument I have heard. It amazes me that in an "engineering" forum this argument could garner 4 votes!

Ladies and gentlemen, ice skates are designed thin for the very purpose of decreasing friction. Please remember pv=nrt and the simple fact that increasing pressure decreases the melting point and melts the snow under the pressure creating water. It is not ice or snow that are slippery, but rather the water that melts under tires, skates, skis, feet, etc. For those of use who live in cold enough regions, as the temperature drops it eventually gets impossible to melt snow under the skates and create a layer of water, i.e. it is too cold to ice skate outside. We also note that as the snow becomes colder, it is easier to walk on and drive on since it is "less slippery".

Snow tires are designed to do more than just keep tread on the road. Research has gone into creating tread designs that move snow and slush away from the center of the tread getting the part of the tire that contacts the ground down to he hard part of the snow or road. Also, research into producing rubbers that remain soft in cold temperatures makes a huge difference. Try driving a snow tire in the summer and watch how quickly you loose rubber. Ask any farmer who works the winter about the difference between a good hose that remains soft and one of those cheap hoses from Home Depot that won't roll up once the temperature drops below 40 degrees.

We bought our last car and the salesman tried to tell my wife that the "all season radials" would be just fine for the winter and that she would no longer need snow tires. I politely laughed and told him that he should really stop telling people things he knows nothing about. Those tires may work most days if you live south of the 40th parallel, but for the rest of us who live in winters with snow and average temperatures well below freezing,we better stick to good snow tires inflated to specifications.

If I really bought your argument, I would have circular steel tires made for my car about 1/16th of an inch wide. Somehow I don't think this would provide good traction on ice. In fact, aren't ice skaters looking for the poorest traction they can get? The only way ice skates get traction is from their edges that carve into the ice. But skaters must angle their blades and keep them sharp in order to obtain this traction. Just use good winter tires and keep them properly inflated.

From a safety perspective only, when you lower the recommended pressure in any tire you cause it to flex more and that is not good for the tire especially if you don't raise it to the recommended pressure soon. After the season warms up , now you have a built in failure waiting to happen. Many people try this and are just lucky.

h

I live in a snow belt in NW Pa. We get 80" every year on average. Just bought some studded snow tires from a small local shop and they pumped them up to 35 pounds. It was 45 degrees F at the time. The other morning the temperature dropped to 20 degrees and the tire pressure was only 30 pounds. (My car has a tire pressure monitor in the dash.)This may be the reasoning behind the pressure increase. By the time the temperature hits 0 degrees, and it will here, I will still have a safe pressure in my tires.

IMHO the type of tire and their condition is more important than a few psi plus or minus. If you care about your friend's safety, suggest he purchase a set of good tires (I like Blizzaks) and rotate to conventional tires when weather permits. The reason for this is because winter tires are made from soft compounds that wear rapidly on dry pavement. If you don't rotate them you may find that in a year or two, your traction is no better than with your normal tires. Attempting to optimize pressure for best traction is a secondary issue.

Hi Welder

That's what started it all. I care and thought to find out if it was a good idea to do what I did back then. I am getting smarter by the post but it has to be remembered that this is a few decades ago. Lots of things have changed.

Drive safely all, not worth experimenting nowadays, it seems, Ky.

Sorry to hear.

So it was the tires that caused this? Or was it that he (bozo) over estimated his driving skills or one of the thousands of other reasons one could lose control of a vehicle?

Great Scott! People, if you don't know, then don't post!

I thought this is what CR4 was for. I did try and google, you know, but the dills were as flat as a deflated tire. Not much substance. Were you actually talking to me? Can't make that out because.......

Gotta go

Best wishes, Ky.

GA. Liked the post.

When I lived in ND, my dad rode "all-season" tires year round. Just matched his speed to driving conditions, and did not mind if a blizzard kept him home bound for 2 or 3 days.

The guys with "muscle cars" (late 60s early 70s era) had wide tires in the summer for looks and street racing, and skinniy tires in the winter for better control and less slidding in the winter. Also, avoid spinning the tires too much, to keep tires cool and dry. A wet tire on snow or ice will have next to zero tracition. This sort of follows an earlier responder with the "soft on hard, hard on soft" advise.

Regardless, I did not know anyone who ran tires outside of the recommended pressure range which is normally +/- 5 psi in the US.

Regards.

I agree with tundrawolf in #18

Bigger grip area is only needed in soft ground like Snow, mud or drifting sand in deserts.

Two tips are used:

1. bigger-width of tyres and

2. low air pressure == this is a common factor for tyre pressure i.e. bigger sizes have lower and smaller have higher air pressure

Bicycles > 60 & cars < 40

Low & Hi Temp tyres are made to work on specified temps.

Have been in sub-zero temperature area you will feel all the flexible items stiff & hard.

Listen their tune by strikng like a bell.

Yu are correct, of course, lower tyre pressure-increase contact area, as per Top Gear antics in Iceland driving across non-frozen lake. Check-out the re-inlfation trick when low-pressure-tyre comes off-bead.

How would I do that, my supreme skipper?

Ah, I get it, I'll go and check the web for a while and then get back to you. Brilliant!

Welcome to CR4.

The place of differential pressures of all kinds and even off road.

Here is the Top Gear tyre moment.

This topic feels quite pertinent at the moment as I've spent the day at home waiting to hear from the garage how much damage I did by skidding into a kerb in the snow. I think I've bent something in the steering as the n/s front wheel seems to have developed 'toe in'.

Cute trick - but the Range Rover one that came up next is all about tyre choice

Can you imagine that guy getting out of his car and deflating (which would help) his tires? And then him using his electric windows, IPMSL.

Good answer for your analysis of tread pattern clearing. Life in the mud is so much simpler than on snow-and-ice. Snow is prettier (than mud) to gaze at from a cozy house, and makes less of a mess of the carpet, but it can make the simplest driving errors fatal.

As I said in my first post on this topic, #47, I believe, the science of traction on ice and snow is the most complicated of all driving conditions. From soft compressible snow, to fluffy cold stuff, to snow/ice which is so close to zero C that any extra energy input will melt it and wreak havoc on traction... there is no simple or easy answer.

We have to simplify the question: ignore handling and tire life, blowouts and stopping. Let's focus on the optimum pressure for initial movement. We can then move on to a single question on stopping in deep -10C snow, then one on staying on a high-crowned icy -20C road.

I suggest we call a truce on all this fun discussion. Pose a well-defined question, so that it can be carefully answered correctly. Until then we have an infinite number of permutations of the original question, and an unmanageable number of somewhat correct answers.

Thanks for the vote. As for your question question; I sorta think it's all been answered bar that groove geometry factor and install a limited slip diff.

Maybe it would be clearer if I ran through what I do?

On the farm 4WD;

I use a 250? x 15", 'self clearing' pattern through summer, as highway, country 'paved' & dirt roads - and rain - are involved.

In winter, be it mud or snow, "when they might not be enough", on go the 215 x 16" full winter treads. When they 'might not be enough', on go the chains. It they "don't look enough" out comes the dozer, or I don't go out.

It is a matter of doing it before it's "not enough".

It may cost me more by choosing 'less mileage' tyres, but I don't hit things or get stuck and freeze to death, well haven't in ~40 years.

And no, I don't "reduce the pressures" but always run at the tyre makers recommended pressure for vehicle mass, (not the vehicle makers recommendation - which may be lower for 'ride comfort' thinking).

Nor would I do that in snow and ice, as the under-inflated tyre gets hotter and a hot tyre on ice is 'unproductive', except on the thinnest film, that melts instantly, and leaves you on paving or frozen dirt. And a properly inflated tyre would 'cut through' that anyway

Hope this helps.

less pressure and basically bald.

That sums me up perfectly. I'll leave the slippn' an slidn' in the hands of others for the time being. Chris will know what to do and has already made his rhyme on the case.

Safe driving all, take it easy, Ky.

Tires for a Tasmanian winter.... this one should be overinflated to keep the driver's pressure to a minimum.

it does not matter 1 bit, thats if you stay home till it melts. if not use chains.