Winter tyres on 21'' wheels

Winter tyres on 21'' wheels

Hello from Switzerland.

It will be roughly 6 months in total here to get my black-21''silver-tanleather-pianoblack-pano-tech-sound-light-pdc-subzero-jumpseats-P85+ (yes, in German we do have long words). So I have time to search / learn loads of stuff since I'm not interested in anything else anymore but the Model S (as per my wife and the kids at least)!
In Swiss winters you definitely want the appropriate tyre / wheel set up. Since I find all 19'' rims ok but nothing compared to 'my' 21''s I was searching for a solution with the big ones. And here is the good news: Pirelli should be able to deliver the brand new 245/35R21 Sottozero 3 XL in November amd the 265/35R21 in December. At least in Europe I presume. For a ridiculous amount of money too, of course.

What do you think? 21'' wheels with winter tyres? A good idea or maybe not?

jat | 18 september 2013

If you are going to have to swap tires anyway, I think I would go with 19" or 20" for the winter tires.

Gizmotoy | 18 september 2013

For winter tires you typically want them to be as narrow as feasible for your vehicle, and diameter isn't that big of a factor. Since the 19"s and 21"s both have the same 245 tire width (wheel width is actually different) as long as you don't have a newer P85+, it should make no difference from a performance perspective.

While the 19"s are going to be much cheaper tires, you have to factor in the cost of buying a second set of wheels. In addition, consider the possibility of hitting snow-concealed items in the snow, which the larger-sidewall 19"s will help protect against.

If it were me, I'd go with aftermarket 19"s in stock-similar configuration.

Brian H | 19 september 2013

Winter 21s are very hard to find.

xradr | 19 september 2013

As I recall from my physics, for winter tires, you want as small a surface area as is reasonable to support car. The weight of the car, distributed over a smaller contact surface area improves traction (increases pressure with contact surface and increases friction). This is among a whole host of other factors that can change traction but is a good explanation for me. In general, would stick with the 19's unless you are going off road in winter (which might merit different vehicle altogether).

You can liken it to ski's I think. The longer/wider the ski (assuming same weight/size person) the faster you go.

jat | 19 september 2013

xradr - 19" vs 21" doesn't change the contact patch -- the only difference is the diameter of the wheel, and a lower profile tire on a larger wheel has about the same overall outside diameter. The width does give you a different size contact patch, so the 265s will have the issue you describe.