October 20, 2014

Lotus Evora Long Term Test – Winter Tyres

I think people thought me mad. Seeing a mid-engined sports car out in thick snow, especially a rear wheel drive one earned me more looks and interest than if I’d been driving along with the car in flames. Usually this would be well deserved, my Esprit with open differential would spin up a wheel at the first chance leaving me stuck on even the flat in the cold. The Evora has the advantage of traction control, an electronic diff and most importantly the Evora IPS Long Term Review car is fitted with the original equipment Yokohama W-Drive tyres in 215/40 R18 on the front and 245/45 R19 on the rear.

These are winter tyres, they’re not snow tyres and it seems that most people, certainly in the UK think they’re only for driving on snow and ice. It turns out that the all purpose (summer) tyres fitted to most cars, most of the time struggle to become useful below 7oC as the rubber compound is designed to be optimum in the warm and dry. The colder they get, the harder the rubber which decreases grip levels. Winter tyres have not only a unique tread pattern but are made from a different compound which is designed to work at these low temperatures, in fact they also wear less than summer tyres in the cold which show accelerated wear when the winter sets in. The UK average temperature is below 7oC from November to April, 6 months of the year so it really does make sense to have a set of summer tyres on the car when it’s warm, winter tyres when it’s cold and you’ll see extended tyre life too, important on a mid-engined RWD car which by definition uses rear tyres fairly quickly.

TLF asked Matt Becker, Lotus’  Chief Engineer of Vehicle Attributes why winter tyres make sense on the Evora (and indeed any car!):

TLF: Why fit winter tyres, what’s the benefit over summer/all year round tyres – Are they really that much different to a top end all year round tyre?

Matt Becker: Winter tyres have a compound which is designed to work below 7oC and therefore winter tyres are not just better for snow they are better for all winter conditions. The general recommendation from most manufacturers is to change from Summer to winter tyres as soon as temperatures fall below this level. Winter tyres in snow conditions are hugely impressive, the block design of a winter is cut into much smaller sections than a summer tyre which gives the tyre the ability to ‘bite’ or deform into the snow at a lower vertical load, if you look/feel the blocks of a winter tyre and stroke your finger across it with not much load you will feel the sharp edges of these sections, this is what makes the tyres work in snow and icy conditions

TLF: How exactly do they work, when should they be fitted and removed from the car?

MB: Depending on countries as some you must change to winter tyres due to law. I personally change my own tyres from November and switch back to summer tyres end of March.

TLF: Alternatively, could you/would you run winter tyres all year around or is the grip too compromised in summer?

MB: No, the winter tyres would be too compromised for summer performance, compare the blocks and compounds of a summer and winter tyres and the evidence is very clear why you use the tyres specifically for the given time of year

TLF: Do they have any effect on the DPM/ABS systems, for better or worse?

MB: The DPM/ABS systems are developed for all conditions, the winter testing that we do is always with winter tyres, and you would not get on or off the frozen lakes with the summer tyres.

TLF: Would you brave an Evora in the snow on summer tyres?

MB: No, you can but summer tyres are just not designed to work in these types of conditions for the reasons given

TLF: Can you still take the car on track on winter tyres?

MB: Would not suggest it, the compound would overheat sooner than a summer tyre and again reasons explained before.

TLF: Any ideas on wear rates compared to summer tyres?

MB: Wear rates are a very difficult thing to judge based on driving style and conditions of use, but generally winter tyres will not wear any quicker than summer tyres of used in the prescribed months.

Since the IPS was delivered it’s been a mild January then snow, snow, snow! When it’s been warm(ish), the car still rides well and when pushed you can feel the softer compound and more dynamic tread which takes a small amount of getting used to. The car feels less planted as the tread has more ‘give’ but once you’re keyed into the fact you’re no longer on P-Zero Corsa’s it’s still exceptionally grippy and just as entertaining to drive. I was expecting more road noise but personally can hardly tell the difference and that’s with well over 1,000 miles in the car so far on various types of journey. In the wet, the winter tyres are superb especially in standing water as the plentiful and wide gaps in the tread and the addition of sipes allow water to disperse very quickly, impressive stuff.

Fortunately we’ve also had a decent amount of snow this February, traditionally winters coldest month which gave me the chance to try the Evora in snow, slush and ice. The multitude of sipes in the tread blocks add plenty of extra gripping surfaces to find traction, the compound stays soft and pliable allowing the tyre to dig into the snow and you can actually drive the car under control. Pulling away with careful throttle input results in zero wheelspin and braking and steering are still completely useful. Even in deep fresh snow the Evora coped well as you can see from the pictures. Push it and of course, physics is as physics does and you’ll be able to slide the car about, activate the DPM and ABS but really, you can maintain control and the available grip from the tyres mean the car is easy to bring back to normal driving.

The tyres are good, they’re not as good as snow chains but are from my recent experience a huge improvement over summer tyres. Continental even go so far as to say that if you can only fit one set of tyres to your car, fit winter tyres as the benefits outweigh the disadvantages over the summer months although as mentioned above, this doesn’t really apply to a performance car but I can see the sense in it.

*As an aside, if you do take your Evora out in the snow ensure that all grills are cleared, even the bonnet grills as the radiators will need to shift a significant amount of hot air out of there and also the roof otherwise that snow will want to fall off at some point and you don’t want it dumped on the windscreen of your or another car!

Want Lotus news updates in your inbox? (It’s Free)

2441 views

Comments

  1. Nobody comments much.

    Interesting read. I live in Japan up in the mountains and we get a lot of snow and it’s generally below 0 evenings from December thru march, day times during jan/feb can see -15 to 20

    Anyway when it’s not snowing and the roads are cleared by a snow plough, no salting, I take my 2-eleven out which I have winter tires

    Tires are great just your hands are not!


Use of this site is subject to our Terms and Conditions. Please see our Privacy Policy. All copyrights and trademarks belong to their respective owners.
The Lotus Forums is an independent website run by Lotus enthusiasts for fellow enthusiasts.