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"Inflate snow tires 4 psi more than recommended tire pressure" #5409971 04/22/20 12:34 AM
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PotatoFarmer77w Offline OP
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[Linked Image]


While looking up lug nut torque spec in a 2016 Mazda 3 today, I noticed the owner's manual says inflate snow tires 4 psi more than the recommended tire pressure. Anybody know why?


1995 Chevrolet K1500 5.7 v8
2007 Ford Ranger 2.3 I4
Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5409997 04/22/20 04:24 AM
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Char Baby Offline
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I see what you mean.
I am going to read it the way I want, instead of the way it's written.
And this is how I am going to read it.

DO NOT:
*Go faster than 120km/h(75mph) while driving with snow tires. OR
*Inflate snow tires more than 4psi more than the recommended tire pressure label, etc.

That's how I read it. However, I think that it is bad advise the way they've written it and it has slipped through the editors and certainly needs an addendum to that page in the owner's manual.

Our resident tire guru(s) may chime in with information that I am completely unaware of.

Last edited by Char Baby; 04/22/20 04:27 AM.

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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410000 04/22/20 04:38 AM
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Over the years there's been lots of problems with language translations. I just bought some folding lawn chairs and one of the 'warning tags' starts with "Do not standing on chair"...

Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410022 04/22/20 05:36 AM
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Lubener Offline
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I think it is because the snows generate more friction with the road surface and generate more heat. I have seen that printed in several manuals going back many years.

Last edited by Lubener; 04/22/20 05:37 AM.

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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410026 04/22/20 05:50 AM
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I think the reason why they wrote that is 2 fold:

1) A smaller footprint is more likely to penetrate the snow and get the tire in contact with the pavement - which always has more grip.

2) Because people don't like to adjust their tire pressures when it's really cold out there, this 4 psi more covers 40°F temperature drop - the tire will never be under inflated.


CapriRacer

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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410041 04/22/20 06:35 AM
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BMWTurboDzl Offline
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The tread compound used for snow tires is really soft so perhaps they've found that an additional 4 psi will compensate for thing such as heat and turning response.

Last edited by BMWTurboDzl; 04/22/20 06:36 AM.

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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410066 04/22/20 07:16 AM
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Danno Offline
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Snow tires are typically installed in a heated garage. The extra 4 psi allows for the decrease in inflation found with colder temps.


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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410082 04/22/20 07:40 AM
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Ded Mazai Offline
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Why didn't you question the first sentence that you cannot go faster than 120 km/h? Does it make more sense than the pressure staff?


BRZ | M1 HM 5W-20, FU | PZ Synchromesh.
Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410099 04/22/20 07:59 AM
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ARCOgraphite Offline
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Mazda unqualified statement is confusing and generally incorrect. Or just plain wrong on the 4psi over placard.


Ne'er on any car Ive owned over 50 years have snowtires provided good traction inflated over placard.

Never. In fact it was dangerous.

Since it doesnt usually dive below 10F often where I am in the early AM. I try to run snows at about 3 psig
under placard Cold (measured typically at 18deg F.) That ends up around 28 - 29 psig .

These have been either 70 series or 65 on minus 2 steel rims fitment.

I would never venture out and drive below -20F.

I could see in cold parts of Canada that if inflated at STP ( say, a garage) you would want the tires over placard due to the 1psig/10deg drop. Then the tires would be 4 UNDER placard

This show the inadequacy of not specifying the ambient temp for a cold fill, and
the assumption of STP conditions. A chart is really needed here.

Now here is a instance where it would be good NOT to read the O.M. smile



Last edited by ARCOgraphite; 04/22/20 08:01 AM.

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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410106 04/22/20 08:03 AM
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bullwinkle Offline
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Only logical reason I could think of is-snow tires tend to have thicker, squirming tread, which a little more PSI can help negate? Otherwise it makes no sense to me!


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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410136 04/22/20 08:42 AM
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JohnG Offline
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I don't see ambiguity in the way it's written. It plainly says the door sticker applies to summer/all season tires and not to snow tires. Pretty simple advice if you ask me.

Now, as to why, that's open to debate.

Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410141 04/22/20 08:48 AM
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Rand Offline
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hyundai owners manuals said the same thing for years.

On a car that recommends 30 or 32psi, 34 or 36 is still fine IMO

now on my jeep that spec 36, no way I would put 40psi in the blizzacks.


2019 Jeep Cherokee Trailhawk 2.0T
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Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410146 04/22/20 08:55 AM
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Quattro Pete Offline
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It's primarily to ensure you're not running with underinflated tires when temperatures significantly drop during cold winter days.


2002 530i   2015 Q5 3.0T   2018 Charger SRT
Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: ARCOgraphite] #5410152 04/22/20 09:03 AM
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Pew Online Content
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Originally Posted by ARCOgraphite

Ne'er on any car Ive owned over 50 years have snowtires provided good traction inflated over placard.

Never. In fact it was dangerous.


In my experience snow tires don't grip properly when underinflated on a passenger car. It becomes very noticeable in deep(er) snow or very patchy spots where the car starts to wander towards corners that aren't properly inflated.

Last edited by Pew; 04/22/20 09:12 AM.
Re: "Inflate snow tires 4 psi more than recommended tire pressure" [Re: PotatoFarmer77w] #5410285 04/22/20 11:45 AM
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Kawiguy454 Offline
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An underinflated squished tread closes the knobs of the tire and it doesn't bite or cleanout the same. And yes thinner tires work better in snow than wide ones.. To the "Follow the manual" nanny types that disagree with the spec i would ask ...so you think you know more than the engineers? This verbiage they have thrown on occasion.

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