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Winter tyres - the ADAC's annual assessment

Sue Pertwee-Tyr said:
Is it quite small, and you have to fumble around to find it when it’s snowy?
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I’ve been in Tony’s car, and my oh my, it’s an extremely well designed cockpit. Everything appears to be placed in an easy to find location, everything is clear, and it’s all good looking too.

Bloody thing goes like stink too.
 
I run all terrain 3PMSF (Yokohama GO15) year round on the Subaru, will handle pretty much anything you’ll encounter on road (and plenty off). I realise everything is a compromise but not had a better all rounder. A reminder for folks to check their tyre pressures in this cold weather as they will drop a bit.
 
SteveG said:
That was the bit I was slightly concerned about however the car coped pretty well and there were no issues, even at the sharp corners between "The Watchers" and Cockbridge. After Cockbridge the snow was gone though, and even through Glenshee (which I think is slightly higher than the Lecht) the road was clear.

It's been snowing quite heavily here on edge of the Pentland Hills and it's currently looking like my wife might have made a mistake taking her SLK to work this morning instead of my car with it's all-seasons on!
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It was the sharp bends that I would have been concerned about. Braemar snow gates to Glenshee were closed yesterday morning too.
 
Suffolk Tony said:
My car doesn't need winter tyres because it's got a "Snow" button on its traction control. You would have thought, in this modern technological world, all cars would have a snow button.
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A well engineered snow function in cars would be a good addition. But it is not a substitute for winter or snow tyres.

The easy way to implement a now function will help with traction, but it is possible do better and it may be that your Lexus does much more.

At its most basic level the snow function should reduce the rate of change of driving or braking force at the tyre contact patch. Reducing peak power and revs does that to an extent, but it should be possible to do better. The snow function should incorporate regulating the braking capability as well (with use fo the engine to stop the driven tyres locking). The difficult part is being able to measure / predict the vehicle speed above ground in a wide range of driving conditions to predict slip accurately enough. So using rate of change of wheel speed and controlling that as a proxy is probably the best method available.

Longer term use of live photogrammetry, LIDAR, GPs and some Kalman filter + vehicle model state estimator etc with assisted or with driverless cars will enable more accurate prediction of speed over ground and hence prediction and control of wheel slips and ratios and rates of change of them.
 
Naa, just get it sideways, window open, fist in the air, shouting out “Hannu Mikkola!”

And there’s a point: early Audi Quattros allowed the driver to switch ABS off. In deep snow and on gravel, a car can sometimes stop quicker with the wheels locked up due to the wedge of material that builds in front of the front tyres. That’d be quite a call to make!
 
Tony Lockhart said:
Naa, just get it sideways, window open, fist in the air, shouting out “Hannu Mikkola!”
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Until those of us not talented enough have a shunt!!

And there’s a point: early Audi Quattros allowed the driver to switch ABS off. In deep snow and on gravel, a car can sometimes stop quicker with the wheels locked up due to the wedge of material that builds in front of the front tyres. That’d be quite a call to make!
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Interestingly Audi did a really big study on this many years ago and found that their systems worked better than switching them off and allowing a snow wedge to build to stop the car.

The snow function really would need to be configurable as the conditions can vary widely and the optimal slip and slip ratios and rate of change need to be adapted for the changes in conditions, just like expert drivers in these conditions do automatically. Most of this could be automated but it would not be easy.... And yes some people will just want to switch it all off and have fun.
 
wulbert said:
I once had a tiny Nissan Micra that was excellent in deep snow and mud.
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I have just put a pair of four seasons tyres on my rear axle after the recent experience of having been overtaken by a Nissan Micra travelling at twice my speed in the snow whilst on my daily commute in my three series.
 
Spraggons Den said:
I have just put a pair of four seasons tyres on my rear axle after the recent experience of having been overtaken by a Nissan Micra travelling at twice my speed in the snow whilst on my daily commute in my three series.
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That'll be fun when you get to a corner and the front wheels want to go straight on and also in the summer when you don't have the same traction.
 
Bananahead said:
That'll be fun when you get to a corner and the front wheels want to go straight on and also in the summer when you don't have the same traction.
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It’s allowed apparently. The front axle has the weight of the straight six diesel engine whereas l can unstick the back in snow just by dropping a gear. Summer driving shouldn’t be a problem as the tread pattern is irrelevant.
 
Spraggons Den said:
It’s allowed apparently. The front axle has the weight of the straight six diesel engine whereas l can unstick the back in snow just by dropping a gear. Summer driving shouldn’t be a problem as the tread pattern is irrelevant.
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If course it's allowed. The car may not handle exactly as you might hope under certain conditions but the same applies if you put new tyres on the front and leave legal but worn ones on the back, or vice versa.
Too many drivers seem to think that they are as close to the edge as Lewis Hamilton as they negotiate that tricky roundabout off the A440 at 35mph.
 
On the roads near me it's lack of grip on the back that'll get you stuck, but lack of grip on the front that'd be more likely to result in an accident I think (especially on some of the very steep downhill hairpins on the Tomintoul to Cockbridge road) - so personally I'd not be keen on having summers on the front and all-seasons on the back. Your mileage may of course vary!

BTW my all-seasons have been properly tested now and I'm been very, very impressed with them compared to the summer tyres. That's included some pretty difficult driving conditions in the Cairngorms which the Cross Climates coped with really well. The only issue I've encountered so far was when parking in front of my cottage where the snow was deep enough to beach the car, so I had to dig it out before leaving. Not much the tyres could so about that of course.
 
Many years ago I had an Mk2 MR2. One day there was snow and I was returning from Bournemouth along the A31. After a while, I had a short parade of front-wheel drive cars behind me. When the road widened to two lanes they thought that they would go past. Unfortunately at that point it also went downhill and I gently dabbed the brakes. The rear went out and I slid perfectly down the hill using both lanes. They backed well off. I did pull over just after that though to let them pass.
 
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