Tire Pressure for Snow Tires

[optical_man]

Interesting, something that I never knew:

In the 2016 CX-5 manual, it states that the tire pressure for snow tires should be set 4.3 PSI higher than the door sticker pressure label:

​

Tire Rack explains some reasons why here:

http://www.tirerack.com/winter/tech/techpage.jsp?techid=168​

 

[quant]

This is a great tip that I used last year, looks like the 2015 and 2016 manuals are the same on these pages

 

[MikeM.]

Tire Rack explains some reasons why here:

http://www.tirerack.com/winter/tech/techpage.jsp?techid=168​

While I've found the "official" pressure listed on the door frame is almost always less than ideal for optimum bare road handling (with summer or winter tires), two of the three reasons provided by the Tire Rack do not hold water because the last two reasons are equally applicable regardless of tire type. Namely that winter tires should be inflated higher because:

2) winter weather is colder and therefore tires heat up less from driving and the natural pressure increase is less.
3) the cold tire pressure might not be measured at cold ambient temperatures due to attached or heated garage.

It's true the CX-5 manual does instruct to increase recommended pressure when running winter tires but it does NOT say to do this with ALL tires in cold weather. Hence the problem with tire racks explanation.

I believe the real reason Mazda (and other manufacturers) recommend filling winter tires to a higher pressure is because winter tires have rubber compounds sensitive to heat and lower pressures can overheat the rubber in the tread causing it to permanently reduce it's effectiveness in ice/snow. My experience with winter tires over the previous 30 years is that they most often perform slightly better in snow/ice at or near the placard pressure. Having said that, unless I need every last bit of snow/ice grip, I run winter tires a couple of lbs. above the placard pressure.

 

[Ride92]

I wonder what effect nitrogen fill has on any of the reasons stated to increase tire pressure? I just got my winter setup installed and Costco filled with nitrogen. I checked psi and all tires are at 36psi. I know nitrogen is much less susceptible to pressure changes due to temps and it also does seep out like air can. Should I increase my pressures a bit across my tires a bit? 40 psi seems high to me

 

[yrwei52]

I wonder what effect nitrogen fill has on any of the reasons stated to increase tire pressure? I just got my winter setup installed and Costco filled with nitrogen. I checked psi and all tires are at 36psi. I know nitrogen is much less susceptible to pressure changes due to temps and it also does seep out like air can. Should I increase my pressures a bit across my tires a bit? 40 psi seems high to me

I put 40 psi on OEM all-season tires when I did the oil change and tire rotation a couple of days ago. I anticipated the temperature will drop further as the tire pressure will drop too.

I saw a report a while ago for comparison between using nitrogen and regular air for tires. On theory nitrogen should be more stable but the test result was surprising. They found there is almost no difference under all situations they had tested between nitrogen and regular-air filled tires!

 

[rwortman]

I wonder what effect nitrogen fill has on any of the reasons stated to increase tire pressure? I just got my winter setup installed and Costco filled with nitrogen. I checked psi and all tires are at 36psi. I know nitrogen is much less susceptible to pressure changes due to temps and it also does seep out like air can. Should I increase my pressures a bit across my tires a bit? 40 psi seems high to me

Air is mostly nitrogen. All gasses behave according to Boyles laws regarding pressure change with temperature. The only reason an air fill might be a little different is the presence of water vapor. If the air is dry, no difference. I don't like my car to ride like it has rocks for tires so I go by handling feel and ride quality. A few psi more is usually needed for winter tires due to the softness of the rubber compound. That said, my last set of snows wore more in the center as you would expect from an overinflated tire. There are trade-offs.

 

[optical_man]

Remember that if your CX-5 came with 19" wheels your door sticker will be for 19" wheels. But, if you change to a different tire size, it's up to you to compensate correctly. I put on 18" snow tires, so I interpolate it this way for what Mazda is recommending in the USA:

[table="width: 500, class: grid, align: center"]
[tr]
[td]TIRE SIZE[/td]
[td]NORMAL (OEM)[/td]
[td]SNOW[/td]
[/tr]
[tr]
[td]P225/65R17[/td]
[td]34 psi[/td]
[td]38 psi[/td]
[/tr]
[tr]
[td]P225/60R18[/td]
[td]35 psi[/td]
[td]39 psi[/td]
[/tr]
[tr]
[td]P225/55R19[/td]
[td]36 psi[/td]
[td]40 psi[/td]
[/tr]
[/table]

 

[brillo54]

Good observation optical_man. To extrapolate further, those of us with P225/70R16 should try 37 psi with their snow tires (at least as a starting point).

 

[Ride92]

Remember that if your CX-5 came with 19" wheels your door sticker will be for 19" wheels. But, if you change to a different tire size, it's up to you to compensate correctly. I put on 18" snow tires, so I interpolate it this way for what Mazda is recommending in the USA:

[table="width: 500, class: grid, align: center"]
[tr]

[td]TIRE SIZE[/td]
[td]NORMAL (OEM)[/td]
[td]SNOW[/td]
[/tr]
[tr]
[td]P225/65R17[/td]
[td]34 psi[/td]
[td]38 psi[/td]
[/tr]
[tr]
[td]P225/60R18[/td]
[td]35 psi[/td]
[td]39 psi[/td]
[/tr]
[tr]
[td]P225/55R19[/td]
[td]36 psi[/td]
[td]40 psi[/td]
[/tr]
[/table]

I was wondering about this since I went from 19's to 17's for the winter setup. So I should go with 38psi for my 225/65R17 blizzak ws80 regardless of the fact that I have the GT AWD, correct?

 

[MikeM.]

I was wondering about this since I went from 19's to 17's for the winter setup. So I should go with 38psi for my 225/65R17 blizzak ws80 regardless of the fact that I have the GT AWD, correct?

That's a good starting point. 38 psi (measured stone cold) will help protect the winter rubber compound from overheating on bare freeway and loosing it's effectiveness. When the roads are extra slippery (like after an ice storm or fresh snow on ice) you will probably find 34-36 psi (again, measured stone cold at ambient temp) provides the best traction/snow ice handling. If measuring in an attached garage you will need to compensate by inflating a bit higher.

Extended high speed driving (especially at warmer temps) is what ruins winter tires. You can't tell they are ruined by looking at them, they just loose their snow/ice effectiveness. So, the faster you will be driving and the warmer the temperature, the higher the pressure should be to avoid this. Never exceed the sidewall maximum.

 

[halfast3]

Good observation optical_man. To extrapolate further, those of us with P225/70R16 should try 37 psi with their snow tires (at least as a starting point).

Which winter tires are you running? I've got Blizzak DM-V1s on Mazda 3, 16" rims and have tried various pressures between 34 & 40 psi in an attempt to reduce their tendancy to track road surface irregularities like those worn by studded tires. So far, the lower end of the pressure range seems best.

 

[brillo54]

Which winter tires are you running? I've got Blizzak DM-V1s on Mazda 3, 16" rims and have tried various pressures between 34 & 40 psi in an attempt to reduce their tendancy to track road surface irregularities like those worn by studded tires. So far, the lower end of the pressure range seems best.

I just got a set of Michelin Latitude X-Ice Xi2's. I have them at 37 psi right now, but less than 200 miles on them. Not sure where I'll end up at.

 

[halfast3]

Just replaced a set of Xi2s with Xi3s on our Golf and had Xi2s on a Ridgeline. They performed very well on both vehicles. I'll be interested to hear if you have any tracking issues with the Xi2s on your CX-5.

 

[brillo54]

Here's a link to another thread where I posted a pic and my initial reaction: http://www.mazdas247.com/forum/show...w-me-your-Winter-Wheels-and-tire-combos/page7 (#94). I'll let you know my thoughts when I get more miles on them (and some snow and ice under them).

 

[madar]

I'm on my 3rd season with my 17" Blizzaks and I'm at 10/32 tread depth on all of them. I average about 6000 miles a year on winter tires. My favorite snow tire pressure is 38 psi stone cold and I have pretty uniform wear across the tread on these. I run 36 psi on my all-seasons. Wheel alignment is key. Winter tires have a softer rubber compound and some wear down to a point where the rubber is more like an all season compound so you will get faster uneven wear if anything is out of whack. These things have pulled me out of some tough spots during the last winter and I wouldn't even think of running all-seasons during winter anymore.

 

[callphy]

i run 41/40 on my 19" Falken HS449, the tire shop set it 41-42 all around when i get it back.

i think 40/39(38) would be better for no load, if the road isnt smooth