winter tire pressure
01-22-16, 12:06 AM
#1
Racer
Thread Starter
winter tire pressure
When I put my 17" wheels and snow tires on the other day, the shop filled them to 40 psi, telling me the cold will lower the pressure ..... I let them do it fully expecting a harsh ride and the car floating ( which my car used to do ) and I would just lower them .....
I was surprised that the ride is fine and the car does not wander at all, but is 40 psi really necessary or even desirable for safe winter driving ?
I was surprised that the ride is fine and the car does not wander at all, but is 40 psi really necessary or even desirable for safe winter driving ?
01-22-16, 04:34 AM
#2
It all depends on how cold the air/tires were when they were filled. If it was filled in a warm garage, it will drop in the cold. I know that tires do drop pressure in the cold as air contracts but its a constant up and down. Car sits outside when its freezing cold, it drops a few pounds. It's driven and tires get warm, the air expands and the pressure rises. If your car has TPS monitors, watch the PSI as you drive a good distance in the winter. It will raise a few pounds. IMO its best to keep them at the recommended PSI. Not sure what tire size you're running but here's a chart out of the service manual.
Unless you're in a situation where your car sits outside and doesn't but a couple miles a day so they don't get warm, recommended psi is what I suggest. just my opinion.
Unless you're in a situation where your car sits outside and doesn't but a couple miles a day so they don't get warm, recommended psi is what I suggest. just my opinion.
01-22-16, 06:38 AM
#3
Pole Position
The tire inflation sticker on the driver's side door jam also provides data. Check pressure in the morning, whether outside or in garage to get accurate reading. 40 psi on 17" snow tires seems a little high, IMO.
01-22-16, 07:04 PM
#5
Advanced
I have been driving on German autobahns for years; I have never seen anyone driving with wintertires at 118 mph.
Would you today in Washington DC drive 70 mph on the highway? Even with wintertires?
OK, sometimes in winter the roads can be dry but even then with wintertires we never exceeded 70 mph. The tires would wear out very fast
Would you today in Washington DC drive 70 mph on the highway? Even with wintertires?
OK, sometimes in winter the roads can be dry but even then with wintertires we never exceeded 70 mph. The tires would wear out very fast
01-23-16, 06:57 AM
#7
Non rated or q rated snow or s I would not buy but these Michelins I would drive100mph for good periods of time got a warrantee most snows do not. Prolly the highest warranteed tire I have seen 45k.
Now its not deep lugged like DMV-1. Here in Wisco ya gotta have a compressor in the garage and bang in or release a few lbs if you want em too wear the best every week check em when ya see the temps fluctuate. That is why nitro is so iffy I aint gonna take my car to the dealer to simply get air on a regular basis though they are fine with it.
I was at the dealer for oil change rotation top off/check tires. Both the techs where telling me about their dads not really being in thier life. I brought it up as my stepkid crashed my Highlander and did not tell me about it when he dropped it off. Tipped em each 10 bucks they where quick lube guys did a nice job both in school for auto mechanics. That 010 Highlander has not been even close reliability to my LS.
Now its not deep lugged like DMV-1. Here in Wisco ya gotta have a compressor in the garage and bang in or release a few lbs if you want em too wear the best every week check em when ya see the temps fluctuate. That is why nitro is so iffy I aint gonna take my car to the dealer to simply get air on a regular basis though they are fine with it.
I was at the dealer for oil change rotation top off/check tires. Both the techs where telling me about their dads not really being in thier life. I brought it up as my stepkid crashed my Highlander and did not tell me about it when he dropped it off. Tipped em each 10 bucks they where quick lube guys did a nice job both in school for auto mechanics. That 010 Highlander has not been even close reliability to my LS.
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01-24-16, 11:45 AM
#8
I have Blizzak WS70's on my 98 GS4 (215 60 16) and keep them at 36 front 34 rear generally.
If you fill them to 40 psi at 50F and then the temp drops to 10F, you will see a fair bit of pressure drop. But if you fill them at 10F at 40, you will be fine.
I use chalk to the sidewalls to the tread and drive it normal and then look and see what chalk is worn away, and it if it worn on the sidewall, too low pressure, if chalk is left on the tread (away from the corner of the tread) I let pressure out. This is the 100% perfect pressure for the weight and conditions you drove. There is NO 100% perfect pressure as the conditions change. You can just get a good reasonable ballpark.
I would rather error on the high side than low side. But the range is still going to be 32 psi (that is my safety bottom psi, due to in an emergency maneuver you could break the bead below 32 psi according to SCCA in my autocrossing days). So a range of 32 to 42 is good, generally 2-4 psi lower in the rear (unloaded car, aka, not carrying heavy loads). FWD (aka wrong wheel drive) always keep 4 psi lower in the rear than the front due to the excessive nose weight.
If you fill them to 40 psi at 50F and then the temp drops to 10F, you will see a fair bit of pressure drop. But if you fill them at 10F at 40, you will be fine.
I use chalk to the sidewalls to the tread and drive it normal and then look and see what chalk is worn away, and it if it worn on the sidewall, too low pressure, if chalk is left on the tread (away from the corner of the tread) I let pressure out. This is the 100% perfect pressure for the weight and conditions you drove. There is NO 100% perfect pressure as the conditions change. You can just get a good reasonable ballpark.
I would rather error on the high side than low side. But the range is still going to be 32 psi (that is my safety bottom psi, due to in an emergency maneuver you could break the bead below 32 psi according to SCCA in my autocrossing days). So a range of 32 to 42 is good, generally 2-4 psi lower in the rear (unloaded car, aka, not carrying heavy loads). FWD (aka wrong wheel drive) always keep 4 psi lower in the rear than the front due to the excessive nose weight.
Last edited by RamAirRckt; 01-24-16 at 12:43 PM.
01-25-16, 05:02 PM
#10
Ok, just have to rant a little (not saying anyone here is buying into it, just more of protecting the consumers here), but don't get sucked up into the dealers selling you Nitrogen for your tires.... Unless you have $$ to burn for no return on the dollar.
Filling tires with nitrogen is a pure waste of $$. Don't buy into the hype. Lets do the math. If our air is already ~78.1% nitrogen and supposedly the non nitrogen leaks out through the tire's rubber (not buying that it will leak any out, but ok, lets say it does for the sake of it) then the remaining ~21.9% of other stuff leaks out, and we are left with pure nitrogen, so we are lower in pressure and top it off, we add in 78.1% more N2 and the rest leaky stuff, to fill in the remaining 21.9% space now we have 78.1% of the nitrogen in the 21.9%, leaving 95.2% pure nitrogen in the tire. So now only a much smaller % can "leak out" in the tire, we top it off again and we are now at 99.8%.... You get the idea.....
Ok, we have nearly pure nitrogen in our tire in a very short timespan. And the next time you fill it, even less supposedly leaky stuff will be there, and higher % of N2.
Its just BS, but a great marketing strategy, but just a way to take your hard earned $$. What you really care about is DRIED air, the moisture in the air is what gives the large psi change in our tires over temp change. So make sure you fill your tires with air from a compressor that has a heated drier on it. Then you will see minimal tire pressure change with temp, but you will ALWAYS see some.
Lets see a test, pure dry AIR and pure dry N2. Bet one would be VERY hard pressed to see a difference in tire pressure from 100 degrees F out to 0 F out on the same tire on the same car that has seen the same conditions.
Filling tires with nitrogen is a pure waste of $$. Don't buy into the hype. Lets do the math. If our air is already ~78.1% nitrogen and supposedly the non nitrogen leaks out through the tire's rubber (not buying that it will leak any out, but ok, lets say it does for the sake of it) then the remaining ~21.9% of other stuff leaks out, and we are left with pure nitrogen, so we are lower in pressure and top it off, we add in 78.1% more N2 and the rest leaky stuff, to fill in the remaining 21.9% space now we have 78.1% of the nitrogen in the 21.9%, leaving 95.2% pure nitrogen in the tire. So now only a much smaller % can "leak out" in the tire, we top it off again and we are now at 99.8%.... You get the idea.....
Ok, we have nearly pure nitrogen in our tire in a very short timespan. And the next time you fill it, even less supposedly leaky stuff will be there, and higher % of N2.
Its just BS, but a great marketing strategy, but just a way to take your hard earned $$. What you really care about is DRIED air, the moisture in the air is what gives the large psi change in our tires over temp change. So make sure you fill your tires with air from a compressor that has a heated drier on it. Then you will see minimal tire pressure change with temp, but you will ALWAYS see some.
Lets see a test, pure dry AIR and pure dry N2. Bet one would be VERY hard pressed to see a difference in tire pressure from 100 degrees F out to 0 F out on the same tire on the same car that has seen the same conditions.
01-25-16, 08:46 PM
#12
I think soley for the dryness of the air. Not for leaks, the car doesn't have air in the tires that long in a race.
If you could dry the air enough for a race car to see the high temps they will see then it is probably worth it, but probably cheaper to just use N2, being it is so plentiful, more so than O2, it just makes sense to use. I don't think the molecule size has anything to do with it, or a very very small reason.
If you could dry the air enough for a race car to see the high temps they will see then it is probably worth it, but probably cheaper to just use N2, being it is so plentiful, more so than O2, it just makes sense to use. I don't think the molecule size has anything to do with it, or a very very small reason.
01-25-16, 10:45 PM
#13
It would be nice if cars would have built in mini air compressors, like the hummers do, instead of going to get them filled some where, sometimes its just a pita.
I heard of some folks with air ride in there car have some form of modification whare they run a tube from there factory air ride compressor to feed air to the tires automatically once it senses air is lost.
I heard of some folks with air ride in there car have some form of modification whare they run a tube from there factory air ride compressor to feed air to the tires automatically once it senses air is lost.
01-26-16, 02:33 AM
#14
They have these systems on tractor trailers but I don't find it necessary for cars. I just carry a great little 12v portable pump in my trunk and check about once a week. I do really like the tpms system that actually tell you how much pressure each tire has.