Most tests - as the one in the first post - show cars driven in extreme temperatures and on ice or snow. I never do that, so this information is irrelevant for me. And I believe there are many motorists in my situation... what we want to know if how safe is it to drive our cars with what the manufacturers call 'Standard tyres' on a clear dry day when the ambient temperature is, say +5 degrees? No one seems to know...
I'm sure the answer would be "it depends"
"Normal" tyres vary hugely, with the most obvious compromise being grip (soft compound) versus longevity (hard compound). You only have to look at the results of group tests to see the variation in wet and dry braking distances (under 'normal' temperatures). My guess would be that some of the softer/grippier premium tyres would be pretty OK at lower temperatures, and that some of the 'economy' ones might be a bit dodgy.
This is one of the reasons I'm a bit sceptical about statistics / comparisons etc. between winter and 'normal' tyres on surfaces other than snow/ice (where there's no doubt about their benefit) - I suspect the outcome depends a lot on which specific tyre is used (as well as how much tread it has ...). When you hear quotes like "performance is reduced below +7C" the key question (which I've never seen answered) is "by how much?". It's also important to remember that "performance is reduced" in the wet as soon as a tyre has less than maximum tread (see
Tyres stopping distances - as tread depth reduces so required stopping distances increases). So if we all aspired to maximum safety at all times we'd be throwing our tyres away every couple of thousand miles, as well as chosing the brand & model based SOLELY on grip (not cost / noise / life / etc.).
In practical terms, I've driven all three of our vehicles at pretty low temperatures without any noticeable difference in grip. By that I mean no ABS cutting in under 'firm' braking, no sign of ESP/traction control intervention under hard acceleration. So on main roads in good conditions (other than being cold) I'm happy to drive reasonably normally. Obviously little-used side roads are a different matter ... you could arrive at a bend and find the road iced over, in which case you are potentially in trouble (even with winter tyres, I suspect).
Having said that, I was in a large and deserted car park last Sunday morning. It was completely frosted over (almost looked like snow), and the temperature was -8C. I did some experimental hard braking on that (this was in our Audi A4), and while I could get the ABS to intervene it was nowhere near as slippery as I'd expected it to be. That was on Avon ZV5s, which are described by the makers as "Performance – General Purpose" with "Outstanding grip in wet and dry conditions" and "Excellent braking performance, wet or dry".
I've driven the SL at -12C (on a bright, clear, dry day), and even with over 300 bhp going to the rear wheels there was no evidence of loss of grip when pulling out normally at junctions etc. However I was well aware of the risk of ice so in general I did drive it quite conservatively.
The Vito (440 Nm torque and RWD) has been driven in all conditions (other than snow & ice) and has always shown great grip on the factory Continentals. In fact I don't think I've
ever had the ESP or ABS cut in. I've also driven it on unrestricted autobahn at +34C ambient (tyre temp. obviously much higher), and I'm not sure how well soft 'all season' tyres would perform under those conditions?
70mph for 30 / 40 mins and my winter tyres where stone cold to the touch straight afterwards.
I could feel the car sliding under me on the approach to this section, and I knew that had I gone any faster through it and veered off course, I'd have been heading nose-first for the water with no idea whether the car would have found enough grip to overcome its momentum. The van driver coming the other way, who'd pulled in up ahead to let me through, didn't look too impressed at the amount of time I'd taken to reach and pass him, but I'm hoping he understood and took a similarly cautious approach through that section.
