Two winter tyres better than no winter tyres?

PobodY

MB Enthusiast
Joined
Aug 23, 2016
Messages
2,536
Location
Stoke-on-Trent
Car
CLK350 Sport
Anyone with a rear wheel drive Mercedes on winter tyres which can out accelerate and outbrake a BMW X3 4x4 in 6" of snow knows their value. As the Scandanavians say, "winter tyres first, 4 wheel drive second", and they see more snow & ice than most.

Russ
I've seen an example of this on YouTube. - Something like an WRX with summer tyres Vs a BMW 3-series with winter tyres.

The BMW wins because it has traction... having said that, it's immensely fun to launch an AWD rally car in the snow even with summer tyres on it.
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
Keeping oversteer in check is the least of your worries in that situation. I don't really want to bore you with the physics lesson required to explain why.

3 pages and nothing but opinions. It is not difficult to understand why a car understeers or oversteers so we dont need a physics lesson. Just a basic explanation to show that yours is the correct opinion and that a car would be worse off for having winters fitted to the rear would be good.
 

Doodle

MB Enthusiast
Joined
May 3, 2005
Messages
5,380
Location
Echo Beach
Car
R129, Leon Cupra 290, BMW R100
3 pages and nothing but opinions. It is not difficult to understand why a car understeers or oversteers so we dont need a physics lesson. Just a basic explanation to show that yours is the correct opinion and that a car would be worse off for having winters fitted to the rear would be good.

If you understand why a car understeers or oversteers, then you should be able to understand why it is correct.

Trying to keep it simple because the actual calculations for this are complex, and it's been 18 years since I had to do (and explain) them. A car during a corner experiences a sideways force, which is shared across both axles. If we assume the force can move the car sideways a certain distance, you can either move both axles that amount (grip being equal), or one axle twice as much if the other does not move (winter tyres on one axle, overlooking that you're now looking at rotation rather than linear slide)

The reality isn't quite as perfect a scenario as that, c/o weight distribution, tyre size and a myriad of other factors. Equally for RWD cars there is a factor of seeking to aid traction, where the FWD has extra weight over the axle to assist and the difference between pushing and pulling a load (if you pull the load will tend to straighten through the CoG, if you push it will seek to rotate around the CoG unless exactly in line).
 
Last edited:

tode

Active Member
Joined
Aug 13, 2011
Messages
296
Location
NW FRANCE
Car
S350 BTEC
You could try putting the winters on the front left and rear right wheels . . . ;)
 

Petrol Pete

MB Enthusiast
Joined
Nov 11, 2016
Messages
5,495
Location
Petrol stations ...everywhere
Car
C55 AMG Wagon
What do your insurers say ? Not sure if things have changed recently but UK insurers were confused about winter wheels being (usually) thinner and smaller in Radius than the stock 'summer' ones, and subsequently classed them as an 'undeclared' modification.

I would go for or 4 myself.
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
Doodle. So to paraphrase. More sideways force is placed on the fronts as the rears can’t share the load, therefore INCREASING understeer. That makes sense and was what I was after all along. Thank you.
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
What do your insurers say ? Not sure if things have changed recently but UK insurers were confused about winter wheels being (usually) thinner and smaller in Radius than the stock 'summer' ones, and subsequently classed them as an 'undeclared' modification.

I would go for or 4 myself.

Yeah things have changed. Insurance wouldn’t be an issue for me or many others. There are still some who are funny about being notified but this is becoming the minority.
 

Delayed Steve

Active Member
Joined
Oct 30, 2015
Messages
374
Location
Cheadle Stoke on Trent
Car
2016 C200 coupe
So you put winter tyres on the back and that helps to get things moving but what happens when you come to stop!
I was always told your front wheels do most of the braking not to mention steering.
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
So you put winter tyres on the back and that helps to get things moving but what happens when you come to stop!

I guess you stop. Not as quickly as with 4 winters but probably quicker than with 4 summers.
 

Wolfie1

MB Enthusiast
SUPPORTER
Joined
Oct 18, 2017
Messages
1,310
Location
Aberdeen
Car
C180 AMG SPORT+, A180 AMG LINE and an FD RX7
What if your trying to steer around someone who's stepped into your path as well as brake?

Russ
Again prob better than you would with 4 summers :p:D:D
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
What if your trying to steer around someone who's stepped into your path as well as brake?

Russ

The more I think about Doodles explanation the less convinced I am. I can’t see how there is a direct relation from the amount of sideway energy transferred from the back to the front (with winter tears). I can see how some of the energy will transfer, making understeer worse but not the full amount. When you consider that understeer is preferential to oversteer anyway then why is this a bad thing?
 

Doodle

MB Enthusiast
Joined
May 3, 2005
Messages
5,380
Location
Echo Beach
Car
R129, Leon Cupra 290, BMW R100
Then I suggest you go away, get some physics qualifications and then work it out for yourself. I CBA to try and explain it to you in terms you will understand any longer.
 

PobodY

MB Enthusiast
Joined
Aug 23, 2016
Messages
2,536
Location
Stoke-on-Trent
Car
CLK350 Sport
If it's a matter of physics, just slow down. - If you're cornering like Stig Blomqvest in the snow, you should expect to have very little control.
 
OP
OP
MB-BTurbo

MB-BTurbo

Active Member
Joined
Nov 13, 2011
Messages
993
Car
B200 Turbo
Then I suggest you go away, get some physics qualifications and then work it out for yourself. I CBA to try and explain it to you in terms you will understand any longer.

It’s the pivoting motion (think direction and distance covered going around the circumference of a circle compared to the centre) and the fact that some of the sideways force will be taken up by the rear tyres that’s making me think there’s more too it.

And I’m sorry, if you’re suggesting you have physics qualifications then you’re not really selling the benefit. I didn’t think it would be that hard to offer further explanation or more insight. Maybe it’s less ‘CBA to explain and more ‘C explain’. Anyway, I welcome anyone else's opinion, assuming it’s constructive.
 

Users who are viewing this thread

Top Bottom