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I'm going to buy and run for the first time a winter rally spiked tyre of 145 80 r13, and I was wondering what pressures do people generally use rallying in low winter temperatures on snowy terrain?

Does running a low pressure increase the grip? Does the air inside increase or decrease volume just like a summer tyre increase pressure inside it as it gets warm?

Note: I am asking about a rally tyre, not a road one

Edit: The manufacturer recommended 1.5bar front and 2.0bar for rear (2.5bar for high oversteer) for my current setup, fwd light car with 75% weight on front

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Flaviu Suciu
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1 Answers1

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Generally speaking, reducing the pressure will be a dangerous idea - underinflated tyres don't stop anywhere near as well, and steering will be more of an issue.

It's actually supposed to be quite a rigid tyre - snow tyres aren't meant to ride on top of the snow (like a large, fat, low pressure tyre would) but cut into the snow for added sideways grip.

Yes, pressure will increase with heat, but because these tyres are probably lower volume than your summer tyres, the effect should not be as marked. You'll still expect about 1 psi for 10 degrees increase in ambient temperature, which isn't as significant on more rigid snow tyres as it is on a broad slick, for example.

Two of my friends who race winter rallycross suggest up to 40psi for short stages and 35-ish for longer stages to take into account the increased temperatures.

Rory Alsop
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