Reply to: Rear wheel drive on snow/ice

[lilelvis2000]

I've seen many rear-wheel drive cars get up our rather steep (10% grade) street, which is made worse because there is a 90% curve near the start of it at the bottom. Its all tyres and technique. Just enough power to get grip -- and no more -- and all season tyres.

My car has 17" rims and Dunlop Sport tyres....absolute rubbish in this stuff. I've been leaving it in the car park at the bottom - along with many others!

There's one lady on our street who floors it all the way up. you can smell the rubber burning...does no good for the transmission and bearings I'm sure.

[the_rangdo]

I drove Mrs O's BMW automatic estate in the snow before xmas and it was one of the most terrifying experiences of my life. Walking or 4 wheel drive is the only guarantee in my book. Also, the older plucky little manual Astra was far superiour than it's newer,more expensive german drivemate

4WD, RWD or FWD, it's still only 4 bits of rubber keeping you on the road.

4WD will get you going better than RWD or FWD but on the wrong tyres you're just as likely to come a cropper braking hard or turning on ice.

Problem with BMW,Merc,etc is they now come on fat (225mm or wider) low profile performance tyres that are meant for summer only. Wide tyres spread the load, might as well be on skis. The plucky Astra will likely have tyres no wider than 175mm with a higher profile and all-season compound rubber.

Right tools for the job, over the past week I've got through the car-park near mini-Rangdo's school better than some Chelsea tractors and a little Renault Clio (I had to push that one out of the way )

[PinkPoshRat]

Nah, forget Beamer, Merks and owdy-doodies - get a 2nd hand Saab

[MarkOD]

I drove Mrs O's BMW automatic estate in the snow before xmas and it was one of the most terrifying experiences of my life. Walking or 4 wheel drive is the only guarantee in my book. Also, the older plucky little manual Astra was far superiour than it's newer,more expensive german drivemate

[the_rangdo]

I ordered Vredestein Wintrac Xtremes

Ditto, got them fitted last week. Took 40 mins just to move the car onto the ramps, got stuck in the snow outside the garage

Do you fit the tyres yourself? I've never fitted tyres (only entire wheels), is it simples?

I got myself a smaller set of alloys off fleabay (narrower higher profile is better in this stuff), tyres fitted to those. Come spring just jack the car up and swap the wheels round.

[BlasterBates]

The rubber compound used probably makes a big difference too.

Well I think the slits are important on ice. All tyres in the UK are all season tyres, and always have been i.e. use a similar compound that is an average of a winter and a summer tyre. But yes the compound is also important comparing a winter with a summer tyre, I think probably less so than between an all season and a winter tyre.

[TimberWolf]

That's not it, that's probably some high performance, normally they're just slits between the tread indents.

The rubber compound used probably makes a big difference too.

[BlasterBates]

Interesting.

http://www.vwvortex.com/artman/uploads/snow_tire.jpg

Presumably all those wiggly lines then?

That's not it, that's probably some high performance, normally they're just slits between the tread indents.

[VectraMan]

Interesting.

http://www.vwvortex.com/artman/uploads/snow_tire.jpg

Presumably all those wiggly lines then?

No wiggly lines on my tyres. Just big manly blocks of solid rubber.

[BlasterBates]

That theory has gone out of fashion now.

What ever the theory I can assure you that when you have slits in the tyres it don't slip. Our road was covered in ice and it didn't slip slightly.How they work, who knows.

[Moscow Mule]

Our Rav4 came with Pirelli Scorpioin STRs which are supposedly "All season" tyres. I've never had to use snow chains (even on 6 inch snow & ice in the alps) and the grip is pretty good.

That said, Mrs MM managed to get the ABS alarm to go off this morning as she was driving normally on an icy road.

So I think it's a combination of the tyres and actually being able to drive in the conditions...

[TimberWolf]

Even the coldest ice releases a film of water when weight is put on it and this film acts as a lubricant between the tire and the ice.

That theory has gone out of fashion now.

[BlasterBates]

Ice Grip

Ice grip requires lots of rubber touching the road, like a racing slick made of winter rubber compound.

This slick would have tens of thousands of tiny slits called sipes cut into it. Sipes are not tread blocks but rather just cuts in the tread rubber. The Pirelli Winter Carving tire has more than 120 metres of sipes in just one tire.

Sipes are the key component in ice grip. Even the coldest ice releases a film of water when weight is put on it and this film acts as a lubricant between the tire and the ice.

http://www.wheels.ca/article/470620


This is the real key to handling icy roads. If you pop round a car park and look at tyres you'll see they've become quite comon. This is fairly recent, I reckon 10 years ago tyres in the UK wouldn't have had these "sipes". However real winter tyres would be made from a different material. I couldn't see the snowflake symbol on the tyre, but it didn't slide on the icy road, and felt like my continental winter tyre. I presume the material is akin to a summer tyre but with the sipes perform well in winter, ie all season tyres that actually work.

[VectraMan]

That's what I mean they have the winter tread (i.e.those tiny slits), but a different rubber that isn't quite as soft as Winter tyre rubber in cold temps, and they are all seasonal.

See the video I posted above. They show that "all season" tyres don't make a lot of difference.

Proper winter tyres have softer rubber, and have smaller blocks designed to move around more and generate a lot more heat. Use them in the summer and they'd overheat in no time, which is why nobody has them here.

A second set of second hand wheels wouldn't cost much, and you're saving your main set from being eaten by all that salt as well. Buying compromise tyres seems a bit pointless.

[VectraMan]

Aha! The philosophy that says cars should be made from glass and have a big sharpened spike sticking out of the steering wheel and pointing at the driver's chest as a way of ensuring road safety.

You have to admit, it would probably work.