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I have switched from a compact car to a SUV that has about 16% bigger diameter for the tires. The tires are wider, too. So far, there has not been so much snow that I could make a final judgement of whether the bigger diameter tires are better in snow than the smaller diameter tires. I however believe that the increased tire diameter helps in snow: at least the bigger tire diameter enables greater ground clearance for the car.

However, in one answer to the question How much can New tires affect the speed on a car? it was claimed that tiny tires are great in snow.

So, which way is it? Are bigger tires (as in bigger diameter) better in snow? What if the car with bigger tires has for some strange reason ground clearance equal to the car with smaller tires?

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    There are so many factors (vehicle, drive-train, tread type, tire type, ratio, etc.) in play here that there isn't a simple "one way or the other" answer. Also, just because the answer on the other post claims "tiny" tires are better in snow, does not mean it is true (there is no reference cited). Can you be more specific in what you are really trying to get answered? – CharlieRB Feb 13 '17 at 20:37
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Narrow tires are considered to be better in snow because of ground pressure. The small contact patch means ground pressure is high, which means there's a greater chance the tire will break through the snow and end up on the road surface.

The size of the contact patch depends on width, diameter (larger tires can have a larger contact patch) and tire pressure (lower pressure=larger contact patch).

For some applications, large tires are used: vehicles meant to be used on deep snow will have very large (high and wide) tires with ground pressure low enough that the car will 'float' on the snow pack rather than sink into it.

You can see this on offroad vehicles in Iceland, for instance:
Nissan Patrol with snow tires

If there's so much snow that ground clearance becomes a problem, you may be better off with large snow tires. But in most countries, they will start to plow the roads long before that level is reached, so the more common on-road situation is a few cm of snow at most, i.e. the situation where you want a small contact patch and high ground pressure.

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Thinner tires tend to get closer to the road surface for traction, while wider tires tend to float on top. Great for sand, not so good for snow.

But any tire with tread blocks works the same way, and will provide better traction than a worn street tire, even if wider.

I honestly don't think the diameter is as important as the width and tread style, as @CharieRB mentioned.

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