Lower tire pressure in heay snow?

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I plan to lower the tire pressure in my daughters FWD SUV from the factory 32 psi to 30 maybe 29 psi to give her a bit more traction. Does anyone know if this works? I already added 4x50lb sand bags over the rear axle. Meant to say "heavy" snow
 
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I've heard of lowering PSI (significantly) for heavy snow, but dropping just a couple of PSI is unlikely do make a noticeable difference, IMO. But I am curious about using sand bags in a FWD vehicle... does that actually help? I can see how it could hurt.
 
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Ive never heard of running lower psi..Id rather stay with stock pressure in winter about 30 psi per door placard. I also never heard of putting sandbags in the trunk of a fwd suv..i know someone i knew did that years ago in a rwd caprice..nothing replaces driving slowly in winter and making sure all maintenance is up to date. I believe the only thing you are doing by going less psi and 200lbs of weight is increasing fuel costs..hopefully Capri chimes in.
 
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I believe the only thing you are doing by going less psi and 200lbs of weight is increasing fuel costs
And increasing stopping distances. But I can see how the sand may come in handy if you get stuck. Just spread the sand in front of your wheels to get you going. Alas, you probably don't need 200 lbs of it for that purpose...
 

Doog

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Originally Posted By: Quattro Pete
I've heard of lowering PSI (significantly) for heavy snow, but dropping just a couple of PSI is unlikely do make a noticeable difference, IMO. But I am curious about using sand bags in a FWD vehicle... does that actually help? I can see how it could hurt.
The SUV is a 2wd FWD 4cyl Rav4 and it is very light. It runs through snow better with 2-3 people in it. All the weight is up front so when you add some to the rear it tracks better. I didn't believe it either until a friend who has the same vehicle showed me in his.
 
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Put the weight in the rear. It's not "traction" to help you move, it helps prevent oversteer, the rear sliding out and you spin. More accidents are caused by oversteer than by understeer.
 
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Originally Posted By: Quattro Pete
I've heard of lowering PSI (significantly) for heavy snow,
This is what I meant... they lowered the pressure from 28 to 8 PSI, but you would certainly not want to ride like that on dry pavement.
 
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I have to run the winter tired on the focus at 44/40 to avoid then wearing the outside. When it is heavy snow or slippery out I drop them to 32.
 

Doog

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Originally Posted By: AandPDan
Put the weight in the rear. It's not "traction" to help you move, it helps prevent oversteer, the rear sliding out and you spin. More accidents are caused by oversteer than by understeer.
This is what I have been told.
 
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Doog that was the way in the 40's & 50's, have read it in old car literature. Put snows on and rest easy.
 
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Do you have any hills in your area? The weight at the back will hurt alot trying to climb a hill. Once in a while I'll be bringing home 2 or 3 90lb bags of feed in the back of our fwd and won't be able to make it up our hill after snowfall. Often just putting 2 in the passenger front seat will make the difference in making it up the hill. ALso in a high speed swerve, the extra weight back there encourages the back end to come out, not what you want at all. I assume what you are trying to get rid of the back end sliding abit in slow corners, for that I'd rather try the rear pressures a bit lower, say 28psi instead of 32 and leave the fronts at 32. The softer sidewalls at lower pressure will help the rear tire patch stick instead of slide.
 
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I put about 200lbs in the back of my 4wd Tacoma for the winter. It is seriously light in the back, otherwise. But a FWD......I cannot see how weight in the back is going to help.
 
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As a native Floridian who grew up in the sandy hill region of Central Florida, I know all too well that lowering your tire pressure works wonders when driving through sand. More than once, we would lower our air pressure down to between 15 to 18 psi and pull through with no problem whatsoever. But you have to have flexible sidewalls on your tires. A heavy six or eight ply sidewall will not allow the tire to "squat" or "spread" on the surface. We would always run regular "car" tires on our trucks for this very reason, when you let out the pressure, the tire would spread and off you would go and we never had four wheel drive. It works well in bottomless sand, but sand isn't "icy." So I suppose it depends on what kind of snow you're trying to drive through. Keep in mind, the concept of lowering pressure for sand is to spread the contact surface of the tire on top of the sand. A tire with rounded "edges" works even better and a lot of fellows would run oversize rims, (wider, not taller) on the back of their trucks. When radials came on the scene, this worked exceptionally well. Another thing to keep in mind when driving in soft sand is not to spin the tire, but to keep the vehicle moving right on the "edge" of spinning. I believe this is what snow driving and sand driving definitely have in common. As far as adding weight is concerned, that always worked well in sand. Sometimes, if we got good and stuck, we would simply lower the tailgate of the truck and shovel it full of sand. That would give us enough weight that we could then pull out of the hole. It's the reason the rear tires on the soon to be world famous "LUV" Machine are filled with water which enables me to drive anywhere on the farm without getting stuck.
 
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Doog

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Originally Posted By: IndyIan
Do you have any hills in your area? The weight at the back will hurt alot trying to climb a hill. Once in a while I'll be bringing home 2 or 3 90lb bags of feed in the back of our fwd and won't be able to make it up our hill after snowfall. Often just putting 2 in the passenger front seat will make the difference in making it up the hill. ALso in a high speed swerve, the extra weight back there encourages the back end to come out, not what you want at all. I assume what you are trying to get rid of the back end sliding abit in slow corners, for that I'd rather try the rear pressures a bit lower, say 28psi instead of 32 and leave the fronts at 32. The softer sidewalls at lower pressure will help the rear tire patch stick instead of slide.
She will only going to school and can take a route with no hills. So I am only putting 100lbs in the back. I also took the tire pressure down to 30 from 32. I have a new set of tires on order. She won't be doing any high speed swerves.
 
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To many variables: 1)Sand,Ice, Deep Snow...Low PSI should help. 2)Rain,light snow...Manufactures Recommended PSI.
 
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The narrowest tire that is rated for the load is usually best in snow. The narrower tire cuts through the snow with less resistance. The smaller contact surface bites the snow harder---say you have 1000# of car weight on each tire (for an example). If the contact area is, say, 8 square inches, you have 1000 ÷ 8 = 125 pounds per square inch of contact pressure on the surface. If you increase that contact surface to, say, 10 sq. inches, you now have 1000 ÷ 10 = 100 psi of pressure on the surface trying to get grip. The bigger tires won't grip as well. The exception is if the snow depth is more than 110% of the the car's ground clearance. In that case you'd want really wide floatation tires, which would be a horror on a slick surface. Stick with the narrowest original equipment size tire for that car. Stick with the factory recommended cold inflation pressure.
 
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Teach your daughter how to property drive in snow and you won't have to monkey with tire pressure. No amount of playing with tire pressure will make up for someone who simply doesn't understand the dynamics of winter driving.
 
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