20" Winter Tyres

[ANDY279]

Hi

Has anyone here tried winter tyres on 20" rear wheels and if so are they any better than summer tyres?
I purchased my X5 (E70) last December and was horrified how bad the car was on standard summer tyres, on many occasions I had no control whatsoever, I would brake and the car would just go side sideways and drift. Trying to reverse on a slight incline was impossible, sideways again! This despite the salesman saying it would be great in the snow and no need for winter tyres, ha! I only bought the vehicle because my 335i Coupe wouldn't move at all if there was anything more than a snow flake in the air and I couldn't get any winter tyres to fit it.
I note that Pirelli offer a 20"- 315/35/20 winter tyre and Yokohama now also have one, but reading other posts and comments on other websites, the general view is that they are a complete waste of money due to the width of the tyre. As these are by no means cheap tyres, around £1,200 for the set, I do not want to throw my money away, but I really like the look of the car on 20's and am not keen to come down in size.
Would there be any benefit in just putting winter tyres on the front, as more choice and lower cost.
If anyone can advise me it would be very helpful. Thanks.

[535dboy]

I'm sure there would still be a benefit remaining at 20" because the compound and tread pattern are different.

I agree the car on summers is bordering on dangerous

I've been on same dilemma with Porsche regarding get a full winter set which would take the car down from 20" to 19", the standard wheel.

At £3.5k it is a lot of money when we could just use mine as my Mrs works for me 3 miles from the office!

[X5Sport]

So you keep her 3 miles away so you can do your 'test drives' eh?

[ChrisABP]

In answer to your questions:

1) NEVER fit winter tyres to just one axle - this is very dangerous and will make the car totally unpredicatble as one end will be generating grip whilst the other has none so it will totally inbalance the car.
2) Any winter tyre will perform far better than an identical sized summer tyre in icy / snowy conditions. Compound, tyre grip and treaf tread block design will all give superior grip even with a 315 width tyre.
3) Winter tyres are usually smaller diameter and narrower for a reason. The more narrow a Winter tyre is the better grip it will offer in snowy conditions as the footprint is smaller and thus will cut through the surface with less resistance. WRC rally cars running on Winter events use just 195 section tyres for a reason!
4) Ideal Winter set-ups are always square (same size front and rear) as the rear tyres are simply cutting through the footprint made by the fronts. When you use larger rears the rear tyres have to also cut a footprint in snow etc so the grip levels won't be as high.

So yes 20" Winters will be better than your summers and you won't find yourself stuck on the M25 or Tesco carpark ramp but smaller 18" or 19" square set-ups will always work better (even if they look tiny!).

To put % terms on the options during winter use:
Summer tyres effectiveness = 25%
20" Winter tyres effectiveness = 75%
18" Winter tyres effectiveness = 95%

Decisions decisions....

Chris 

[Nat]

Hi,

Absolutely no question , winter tyres will be much better than summer tyres.
A few points for you to digest.

1. Winter tyres have a high silica content, which means the rubber remains soft  in low temperatures.
2. With regards to the use of narrower winter tyres as mentioned above............yes narrower tyres work better in certain circumstances. The thinking here is that a narrower tyre can dig down through the snow on to the surface below and get better grip. I think making comparisons all be it for illustration with a rally car that races on loose surfaces is not ideal. In the arctic they use much bigger tyres but again thats not really  a fair comparison.
3. Winter tyres work in a different way. You will see that each tread block has grooves in it. The technicals are that snow gets wedged in the groove and has a paddle effect. Think paddle steamer. You could thus argue that the wider the tyre the more " paddles "you have and the more grip you will have.
4. In reality there will be little difference between a 275/295 or 315 tyre that you will notice. The narrower tyre you go the more choice you will have thats all.
5. In general we drive on gritted / trated roads . There are of course situations where we come accross an untreated road or some of us live in very rural areas. If you encounter ice most tyres wont be able to dig down so there will be no difference
6. The wider the tyre the more grip you have and the faster your car will stop, so thats an argument for a wider tyre over a narrower one, especially on treated surfaces.
7. This isnt about tyres but about ABS. Back in the 80's, audi quattros had switchable ABS ( I.E you could switch it on or off as you wished ). In snow it was proved that by allowing the wheels to lock, it had a snow plough effect allowing snow buildsup in front of the wheel  and that it would  stop you faster. I am not aware of any manufacturer that currently lets you switch your ABS on/off. I liked having the choice myself personally.

We could all spend agres making points for and against 285 or 315 rubber. All you really need to know is that winter rubber makes a very big difference over summer rubber in the winter, and I think you know that anyway. Also we tend to drive a lot slower under winter conditions. Buy according to your budget and looks requirements.

I have the pirelly snow and ice 315 rear tyres just in case you were wondering. I bought a set of replica wheels of ebay for £600 and managed to buy the tyres for £1100.............a lot cheaper than buying it from BMW for £3500 , so it is possible to save sone money if you shop around. Also plenty of second hand sets on ebay/other places.

Regards,
Nat.
Nat

[ChrisLux]

The salesman who told you Winter tyres make no difference is an arse !! Would you rather your vehicle looks nice on 20'' tyres and in a ditch with £5k damage , or doesn't look quite so nice and works the way it was intended ??

ChrisABP summed it up perfectly for me .

Nat , your point 4 is incorrect , you will notice difference between 315 / 295 / 275 , I've tried them all and the
narrower is the better in ice/snow . However , on 'clear' roads you will notice the narrower tyre makes it seem
a bit more 'boat' like in the handling dept.

Good luck in your choice Andy

[ANDY279]

Thanks for all the advice, it's been really helpful. Definitely going to buy winter tyres now, but I have one more question. Will the rear wheels take a 275/40/20 tyre, so that I have a square set up? Thanks.

[ChrisABP]

[quote="ANDY279"]
Thanks for all the advice, it's been really helpful. Definitely going to buy winter tyres now, but I have one more question. Will the rear wheels take a 275/40/20 tyre, so that I have a square set up? Thanks.
[/quote]

Afraid not - the OE rear wheel is too wide for a 275 section tyre.

But I wonder if you could fit front wheels all round on an E70..... You could try one of your front wheels on the rear to see and then buy another pair of fronts so you have a 20" square set-up.....

Chris

[ANDY279]

Ok, this is becoming a problem. I've managed to get 315/35/20 Pirelli Scorpion Ice & Snow tyres from Camskill's, which are run flats. They don't have the 275/40/20 in run flats, only standard. I have found  a couple of companies that have this size as run flat, but they are quoting £4-500 per tyre. I only paid £325 each for the rears. Would it be a problem to have non run flats on the front?

It better bloody snow this year!!!

[Nat]

I have those tyres. To be honest £325 is a great price for the 315 tyres.
Using non run flats shouldn't make that much difference , the sidewalls will be softer but I wouldn't think its a must not do if you have them accross the same axle, although Its not something I would really want to do. I am not an expert in that field.
Look at the third link below , run flats from cardiff for £317 ish.
Hope it helps

http://www.ebay.co.uk/itm/20-275-40-20- ... 377wt_1019

http://www.mytyres.co.uk/cgi-bin/rshop. ... =#mpSearch

http://www.ebay.co.uk/itm/275-40R20-PIR ... 1994wt_998


Regards,

Nat.