Cold Tires vs Cold Roads

[kgb_agent]

It's that time of year again. For those in the north you know what I'm talking about: it's freezing when you get up and it's dark on your way home from work during the week. For me this means my NSX only sees the light of day on weekends when the roads are dry. So in other words, not frequent enough.

But when I do hit the backroads on that rare January Saturday I realize that adhesion ain't what it was back in the summer on the stock rubber. So my question is how influential to the car's grip is tire temperature vs road temerature? If I had to approximate, I would say that grip is 30% lower on a 35-degree day vs a 75-degree day. What about warm tires on cold roads? How do you who attend track events in the colder months deal with this issue? (BTW I run Bridgestone RE010's).

 

[docjohn]

Grip involves the coeficient of friction of both surfaces.IOW I have no idea of the percent contribution of tire vs road seperatly,but I would doubt that your warm tire cold road would produce any more grip than a cold tire cold road senario(in the real world)So what I do is make sure I have good air pressure(since tires loose pressure as the get colder) and just drive and test grip with braking and little wheel corrections.Just like what I do on my first out laps at the track.But, and this is a big but(I like big buts),, tire model and compound has everything to do with winter grip.Plus if there is any frozen precip on the ground all bets are off.personaly I will only drive on dry frozen roads,but I have been surprised with a loopty do on an ice patch with so2 or 3's.

 

[j14nsx]

I did a track day last Feb in very cold weather,barely above freezing. My tyres still came up to 50degC after a few laps.

 

[Tony Montoya]

I've had excellent traction in -3C weather.

Ferrari will not let any of their cars out on Fiorano sp? until the temp hits 41F.

 

[NSX-Racer]

I've had excellent traction in -3C weather.

I guess that depends on the kind of tires. Here the common sense is that summer tires loose their grip significantly when the ambient temperature is below +7 C and that you should use winter tires. Usualy the street temperature is lower than the ambient temp.

Of course winter tires have softer compounds to give you better grip.

 

[apapada]

Here is how a "grip" evolves versus tire operating temperature on a typical winter tire (blue) and summer tire (red). This data is for illustration only, and does not represent real data of real tires. As you see the summer tire provides very little grip at low temperatures and once on the hot side it tends to loose its grip pretty fast as the tire becomes "greasy" due to thermal breakdown. The winter tire on the other hand has a similar shape curve that peaks earlier (colder temperatures) and does not go as high. The most important temperature is the one inside the tire tread. If it's an open wheel car, the ambient air temperature will play a much bigger role than on a closed wheel car. On a closed wheel car, the track temperature is of course more important than ambient. Ambient or track temperatures only influence how fast that optimum operating temperature is reached in the tire tread... Again the following curves are for illustration only...

 

[W]

Your tires will reach a point where a more winter-like tire will grip better. I can remember a time where I lived in the coldest nation's capital in the world and had better grip running snow tires on cold winter roads regardless of there being snow/ice on the roads.

 

[apapada]

Your tires will reach a point where a more winter-like tire will grip better. I can remember a time where I lived in the coldest nation's capital in the world and had better grip running snow tires on cold winter roads regardless of there being snow/ice on the roads.

this is correct. it can be undertsood and explained by looking at the above graph. Where the two curves cross-each other, at the left of that point, the winter tire is better (blue curve higher then the red curve) whereas at the right of that point, summer tire is better (red curve higher than blue curve). The X axis are the temperatures