Winter tires do you over inflate

I slightly over inflated my Michelin Alpin A4s last year but only by a couple of psi. Had no problems with handling and the mpg was pretty good. I guess you need to balance safety vs fuel economy with winter driving.

 

I used Michelin X-ice in 195/65R15 size last winter, set them around 42 psi, work well. I think max sidewall is 51.

 

For those that answer it'd be a good idea to mention how you check tire pressure (In a garage or outside? At what temperature?).

I say this as a drop of 10 degrees F will lower the PSI by one (rough rule of thumb).

So if you set the tires at 35 PSI at 70 degrees in a shop or heated garage and then drive out into 30 degree weather you'll be closer to 30 PSI after you let it sit in a parking lot somewhere.

Similar if your home garage is 50 degrees F and the outside temp is 10 degrees F.

I don't use winter tires as I'm far enough south that "All-Season" tires literally work year round for me but I consider temp when I inflate and in the winter I don't over inflate quite as far. Most of the year I'm doing 48/45 (front/rear) but in the winter I'll do 45/42 in my garage and I never check tire pressure at below freezing temps. So I'm dropping the garage PSI by 3 for winter but on the road the difference may be higher depending on how cold it gets outside.

 

Running my studded snows at 38 psi. Check the pressure in heated garage.

 

I run 40/38 in my winter tires. Since my 2 motorcycles take up the garage, I do it in my driveway, in the morning before driving anywhere. I *try* to keep up with it on a monthly bases, but typically weekends are the only times I have to check them. I try to find a morning that is consistent with the average temperatures for that month. We have that stray 60 degree day sometimes in January, but I would wait for a day with a high temp closer to 30ish.

 

No.

Under-inflation flattens the tire making it softer. This gives a wider grip and a softer ride. This is done in sand.

Over-inflation rounds out the tire making it harder. This causes a narrower gripping surface and a harder ride.

Both under and over inflation will shorten the lifespan of the tire.

You will not see any benefit from over-inflation on ice or snow. A harder ride and possibly better gas mileage, but the tire's grip on ice will be less. Do not do this.

 

Actually, under inflation is a bad idea on any surface but sand.

For wet conditions it is best to maintain proper inflation. An under inflated tire will increase the risk of hydroplaning because water cannot be evacuated fast enough and the center of the tire will compress and lose contact with the ground. In this case it is better to be over inflated than under inflated.

Tire Tech Information - Air Pressure vs. Wet Performance

Tire Tech Information - Air Pressure - Correct, Underinflated and Overinflated

Keep in mind that the old idea that overinflating your tires increase wear or cause uneven wear does not hold true for the Prius or the size tires they commonly use. It has been demonstrated over the years and by a larger number of Prius owners that higher tire pressures increase mpg, increase tire lifespan through more evenly distributed treadwear and decreased hydroplaning. This was not the case with larger truck tires, however, so inflation must be considered on a case by case situation.

 

If pushing the pressure up a bit makes the tire taller/narrower, and this is very slightly, isn't that going to improve snow traction? Narrow tires behave better in snow I think.

 

It would, a bit.

Are you driving through 4 inches of fresh fluffy snow? Or on pavement that has been plowed? Big difference.

4 - 6 inches of fluff and the idea of taller/narrower tires to reach down through it [and to keep your undercarriage higher to avoid the snow from lifting your vehicle weight up off the tread] is a good thing.

But if you are driving on packed snow [like across a frozen river or plowed pavement] then wider is more grippier.



Here we normally see one storm per week. They are usually fairly quick and mostly at night. By sun-rise the next morning the skies are clear and sunny. They do not salt our roads, they just plow them. So it leaves a smooth surface which fills in potholes. We try to avoid driving during the storms, so we rarely drive in the fluff.

In thick fluffy snow the small light-weight vehicles have a tendency to be lifted by the compacted snow pushing up on the undercarriage. Little weight is left on the tires so they lose traction. We have experienced this many times previously with other small commuter cars. It is better to simply wait for the plows to remove the fluff.



Driving on the packed layer of mixed ice and snow that is left by the plows, is okay with fatter tires.

 

I just try to keep my year-round psi the same as much as possible. In winter I assume temps will average 25-30 degrees/F and adjust psi accordingly.
Technically, they would be over-inflateded when the vehicle sits in the 50 degree/F garage overnight, but that's not when I need them to perform.

 

OK, so which is it?
On snow (and ice), is it safer to over-inflate or do door-jamb spec?

(but if it's safe both ways, of course I'll over inflate to save gas)

Thx,
PNB

 

I'm still setting my X-Ice 195/65R15 around 42 psi. Then you can pretty much leave them alone all winter. With our low profile 17" OEM all-seasons I stay lower, say set them around 36, but the 15" are more able to absorb shocks.

 

42/40 ?

 

I just set them all the same; makes for less hassle when rotating.

 

2.3 winters now with Mich. X-Ice Xi3 on my Prius C (175/65-15). I run Max sidewall up front (51psi) and 49 in rear. Checked every 2 weeks in garage under house (~50F, 10C). Used to be a skier so I know a bit about traveling in fresh snow. I haven't tried an A/B comparison; that is, driving around in the same storm with different pressure, but I've been happy with snow and ice performance. And really surprised with the better-than-expected MPG with these tires. It's important to note there can be WIDE variation in traction in winter. I frequently brake test for grip when there's no one else around.

 

For safety it is best to use the specified pressure.. That is what the tires are designed for.

Under-inflation flattens the tire making it softer.for a smoother ride.

Over-inflation makes the tires harder and gives you a rough ride.

 

Higher Tire Pressures for Winter Driving:

Winter Tech Information - Higher Tire Pressures for Winter Driving

 

Yes, I always overinflate.

I set my tires 44psi at the beginning of the winter season (when I install them and it is still above freezing). That way even if the temperatures go down all the way to -30c, they won't ever go down below 35psi.

I've done this with all my cars ever since. Previously used Michelin x-Ice before. Currently testing Hankook Optimo 4s (all season tires) with the minivan. So far so good on the Hankooks even with all the snow we've been getting.