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Post by the light works on Dec 8, 2014 5:04:51 GMT
I know we've had a few standalone myths about tires, but perhaps a catchall thread would be good.
I think it was on the old boards, we had someone insisting the width of the tire made no difference on traction because the contact patch would always be the same for the same weight of vehicle. I'm inclined to think that would only be valid if all tires were essentially balloons; rather than being formed to present a flat cross section of tread.
I also remember seeing a thread stating that the tire pressure in PSI was a guide to how fast you could go through standing water without hydroplaning.
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Post by ironhold on Dec 8, 2014 6:00:10 GMT
I'd suggest that the guys also look at the bit about how over-inflated and under-inflated tires can damage both tire and vehicle, if only to actually remind people that this is a serious issue.
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Post by GTCGreg on Dec 8, 2014 6:03:46 GMT
There are so many different tire parameters from one tire design to another such as diameter, width, thread pattern, material hardness, etc, that it's impossible to say that changing one thing, such as inflation pressure, will have the same effect on all tires.
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Post by the light works on Dec 8, 2014 15:05:41 GMT
There are so many different tire parameters from one tire design to another such as diameter, width, thread pattern, material hardness, etc, that it's impossible to say that changing one thing, such as inflation pressure, will have the same effect on all tires. true, but the results of significant over or underinflation WILL be consistent. |
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Post by silverdragon on Dec 15, 2014 8:59:17 GMT
One thing I would like to see them demonstrate is the inability of a normal road tyre to deal with a fresh wet surface.
The idea, you had a long dry spell, summer maybe, and you get the first rains of autumn...
I know by experience that this first rain washes off all the dust dirt and oil from the summer, but, as its doing that, it turns the surface to an ice rink, often more slippery than Ice, and especially because people have forgotten how to drive in the damp.
Tyres have problems gripping in the wet, thats no myth, but is it all the tyre, or is most of it human caused...
Or is it as I suggest, fresh rain washes dirt across the road.....
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Post by the light works on Dec 19, 2014 18:07:44 GMT
One thing I would like to see them demonstrate is the inability of a normal road tyre to deal with a fresh wet surface. The idea, you had a long dry spell, summer maybe, and you get the first rains of autumn... I know by experience that this first rain washes off all the dust dirt and oil from the summer, but, as its doing that, it turns the surface to an ice rink, often more slippery than Ice, and especially because people have forgotten how to drive in the damp. Tyres have problems gripping in the wet, thats no myth, but is it all the tyre, or is most of it human caused... Or is it as I suggest, fresh rain washes dirt across the road..... I have seen it written up that the first rain soaks all the gunk loose - and the gunk becomes slimy until it is scrubbed off by tires, or flushed off by the volume of rain. being in California, I can see it as a good opportunity to test it if they can get a fairly high volume road to themselves for a day or so. |
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Post by wvengineer on Dec 20, 2014 12:30:37 GMT
How about the idea that narrower tire are better in snow, wider is better on ice? For this they would need to stick to one tire design and simply vary the width. May give them a change to make up for butchering the driving backwards in snow one from several years back.
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Post by the light works on Dec 20, 2014 14:00:26 GMT
How about the idea that narrower tire are better in snow, wider is better on ice? For this they would need to stick to one tire design and simply vary the width. May give them a change to make up for butchering the driving backwards in snow one from several years back. you know - that is one episode I have never seen. however, I can attest for a fact that with a front wheel drive car, backwards is better for traction; at least on an upgrade. |
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Post by silverdragon on Dec 20, 2014 14:39:36 GMT
That was started by ME, (and others).. a friend and relative at the TRRL in England, I asked if they would research tyres and fresh rain... they did.... no surprises, less traction on the gunk.
It has changed how some people look at tyres.
Some tyres got some re-design, into not just water shifting, but more mud shifting.
This is the all-weather tyre, some call it a winter tyre, but in UK and europe, they are more all year round tyres, minimum depth 1.6millimeter tread all over is just about legal.
It has also changed road design to put more grit and abrasives "Where needed", you may see patches of high traction road surface, "Super grip", just before (and through) junctions, Pedestrian crossings, and on tight bends.
Shell Super-grip, back in the last century, was a road surface I first encountered under test at a race track in UK, it was laid to be tested as a road surface.
It was all good.... it got developed more, and is now a better road surface used all over the place.
Tyres in snow.
You need grip.. narrow tyres digging through the snow?... less grip.
I dont know on that one, for sure, but what I know already says the wider tyre is better...
I suggest it depends on the driver.
If I have a large heavy goods vehicle on snow, I have choices.
I can either raise an axle to put more weight on the drive wheels, drive carefully on what I got, or chain up the drive wheels.
On no occasion have I raised an axle... the more tyre surface gripping the better.
In my own estimation, slowly and gently, no sudden changes of anything, drive as if you have a basket of eggs on your lap.
Spinning the wheels gets nothing done at all.
If you spin a wheel and did a ditch under the tyres, you then have to climb out of that ditch?...
Of course, the sensible option is to know when you are flogging the greasy spot where the cart horse once died?...
If the weather is that bad, look at how urgent your journey is.
But as to which tyres work best?..
My option is always choose a good tread pattern that has lots of grip, inflated to the right pressure, and ease it through slowly. BIGGER tyres are better.... until you get to Monster truck size, which is, well, not that good... or is it?...
Just how would a Monster truck, driven carefully, manage on a surface where nothing else but a snow mobile gets grip?...
Now on to that tyre and sand/snow vehicles that use lower pressure tyres that spread out all over the place to give more surface area....
Ask those who live in Iceland and Canada and other snow environments that use 4wd and HUGE balloon tyres at low pressure?...
Would they swap for thin tyres?..
I suggest they have tried and found a bigger surface area, something like the use of snow shoes, is better, spread the weight out, and keep on top of the surface...?...
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Post by wvengineer on Dec 20, 2014 15:25:03 GMT
How about the idea that narrower tire are better in snow, wider is better on ice? For this they would need to stick to one tire design and simply vary the width. May give them a change to make up for butchering the driving backwards in snow one from several years back. you know - that is one episode I have never seen. however, I can attest for a fact that with a front wheel drive car, backwards is better for traction; at least on an upgrade. For me that was their jump the shark episode. It was bad in just sooo many ways. The "load noise causing an avalanche" myth, they state that there was recorded occurrences of it in history, but since they can't replicate it on a mountain with a low avalanche risk, they call it busted. WTF? The more traction in reverse, they admit that Kari and Grant had never actually ever driven in show and have them drive way speed though a snow field to see how it works and surprised when no one can control a car. The hilarious part was during their pretesting, they try to want to measure reverse force on ice with a car. so they take a linear scale and instead of attaching chain to the frame of the car, they wrap it around the radiator and are shocked with they completely destroy the front end. It wasn't one of their finer 40 minutes Silver, the logic with the snow tire width is that in deep snow, a narrower tire will knife down into snow and actually get down to pavement providing better traction, whereas a wide tire will ride up on snow with lower traction. I haven't had the budget to do anything resembling testing this. It is a common belief in my area, so could make for a testable myth for the show. |
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Post by silverdragon on Dec 20, 2014 15:38:54 GMT
Yes a testable myth.
To expand my thinking, you dig down, you now have more traction on the road, but what have you lost, when you factor in you now have to push deep snow out of the way in front of the tyre to keep that grip on the snow.
What you gain on the roundabouts you loose on the swings?...
And then what happens when the snow is deeper than your axle depth....
If you are bumper deep in snow, you now have to gouge a whole car width of snow away to go forward.
On a low slung car, priceless......... what you have there is a sledge.....
For my experience, see the show Ice Road Truckers, those guys are experienced in moving heavy loads in the worst of conditions, much more experienced than I am, and my thinking agrees with them?... stay on top and slow the truck down..
So you usually do 30 on this road... today, if you get 15, you are going way too fast for the conditions.
On some stretches, I have done less than walking pace.
On others, 10mph for 5 miles was about right...
And yes, the teams attempts to drive in snow were hilarious... they showed pure rookie sh-1-t levels of competence, but, as they had never tried before, I dont think it was that bad, they did highlight how difficult it was for a first timer, and that was good.
If even them, who were testing in good faith pre warned and taking care can do that?...
They also didnt do that bad compared to some I have seen..... [shudders at the memories...]
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Post by the light works on Dec 21, 2014 15:25:33 GMT
Yes a testable myth. To expand my thinking, you dig down, you now have more traction on the road, but what have you lost, when you factor in you now have to push deep snow out of the way in front of the tyre to keep that grip on the snow. What you gain on the roundabouts you loose on the swings?... And then what happens when the snow is deeper than your axle depth.... If you are bumper deep in snow, you now have to gouge a whole car width of snow away to go forward. On a low slung car, priceless......... what you have there is a sledge..... For my experience, see the show Ice Road Truckers, those guys are experienced in moving heavy loads in the worst of conditions, much more experienced than I am, and my thinking agrees with them?... stay on top and slow the truck down.. So you usually do 30 on this road... today, if you get 15, you are going way too fast for the conditions. On some stretches, I have done less than walking pace. On others, 10mph for 5 miles was about right... And yes, the teams attempts to drive in snow were hilarious... they showed pure rookie sh-1-t levels of competence, but, as they had never tried before, I dont think it was that bad, they did highlight how difficult it was for a first timer, and that was good. If even them, who were testing in good faith pre warned and taking care can do that?... They also didnt do that bad compared to some I have seen..... [shudders at the memories...] to my thinking, there are three basic sorts of cold-white affected driving. there is hard packed snow, deep accumulated snow, and slush. in slush, you want your tires to punch down through it, and mash it out of the way - otherwise, you are hydroplaning. in deep accumulation, some punchdown is okay - but too much, and you are sitting on the bellypan with your wheels digging holes. on hard pack, you have to treat it as ice - you want lots of soft rubber looking for any irregularity to get a grip on. |
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Post by silverdragon on Dec 22, 2014 10:04:56 GMT
Slush and very soft snow, yes indeed, you have it right, but if you are "Digging down" then your average winter tyre will do that, your job as a driver is to know to slow the truck down and give your tyres time to work...
Its the same as aquaplaning, too fast, you will aquaplane on slush, which acts the same as water, just a little slower, so, you should drive a little slower.
Ice, yes, you are looking for slow grip.
You WILL get grip, if you accept that the tyre pattern will press on the ice and melt it a little, therefore creating ridges to grip on... not much, but enough....
Or so it is believed?.. can that be shown in some way, or is it a myth to be busted as well.?..
Again, I have knowledge from experience, that is not general common experience, especially if you live in a place where it doesnt snow or freeze.
Each successive tyre will form a ridged surface, roughened up, and that gives grip to all following tyres, be they yours or the next truck.
Worst scenario is a little sun that melts and re-freezes the surface.
Then you have "Polished glass".
So your fourth white is re-frozen....
And there are more. The Inuit people apparently have over 100 names for different snow....
My worst is driving on re-frozen where it has layered.
Thats snow, a little melt, frozen, snow, a little melt, frozen and repeat.
Some of it is light, some of it gets hard packed.
Knowing what the weather is today is good, knowing what it has been over the last week is priceless......
It crunches under foot, and you have no idea whats under all of it, or even if it will bear your weight.
Its many years since I did driving in Canada, I may have to take a little refresher course before I do that again, you tend to forget some of it unless you are doing it every day.
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