Tire Pressure
11-09-2011, 07:54 PM
#1
Super Member
Thread Starter
Tire Pressure
My E350 tire pressure decreased. I don't drive the car much during the week. Most of my driving is on weekends. I adjusted the pressure less than 3 months ago and it has now decreased 3-5psi. Is this normal?
11-09-2011, 07:58 PM
#2
Super Member
Mine did the same. I guess due to the cooler weather my TPMS warned me of a low pressure tire today. Seems like I put air in the same tire about 5 months ago.
11-09-2011, 10:01 PM
#4
Super Member
Nitrogen would be good, but not at mercedes dealer prices.
I have run flats on my bluetec (hate them, but that's what Mercedes gives us) and they can vary by 3 psi if the outside temperature drops by 10 degrees. Since I run them at 35 psi, on a cool day, they start at 32 and that's pretty low. When they heat up, their back at 35 psi. It's very hard to keep these tires at any set pressure on a day to day basis.
I have run flats on my bluetec (hate them, but that's what Mercedes gives us) and they can vary by 3 psi if the outside temperature drops by 10 degrees. Since I run them at 35 psi, on a cool day, they start at 32 and that's pretty low. When they heat up, their back at 35 psi. It's very hard to keep these tires at any set pressure on a day to day basis.
11-09-2011, 10:16 PM
#5
Super Member
Nitrogen is a total joke, especially if you pay for it. Remember folks that everytime you fill up from the "air" pump you are getting roughly 78% nitrogen free. As the sales pitch goes nitrogen is a larger molecule so it is less likely to leak out. Well hay then the only thing leaking out must be the oxygen and before long you'll have pure nitrogen in the tire anyway. lol. Just another snake oil so auto dealers and tuners can make more of our money.
11-09-2011, 10:18 PM
#6
Senior Member
Nitrogen would be good, but not at mercedes dealer prices.
I have run flats on my bluetec (hate them, but that's what Mercedes gives us) and they can vary by 3 psi if the outside temperature drops by 10 degrees. Since I run them at 35 psi, on a cool day, they start at 32 and that's pretty low. When they heat up, their back at 35 psi. It's very hard to keep these tires at any set pressure on a day to day basis.
I have run flats on my bluetec (hate them, but that's what Mercedes gives us) and they can vary by 3 psi if the outside temperature drops by 10 degrees. Since I run them at 35 psi, on a cool day, they start at 32 and that's pretty low. When they heat up, their back at 35 psi. It's very hard to keep these tires at any set pressure on a day to day basis.
11-09-2011, 10:37 PM
#7
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2012 S350 Bluetec 4Matic, Diamond White, P2
It is not uncommon for a tire to lose some pressure over time. Once the temps drop tire pressure will drop about 1 lb. per 10 degrees IIRC. So if you filled your tires when the ambient temp was 80 and it is now 40, it would be expected that you would lose 4 lbs +/-. Always check the pressure when the tire is cold (or driven less than 1 mile).
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11-09-2011, 11:10 PM
#8
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2005 Audi S4 MT6
Well if your cars are brand new then you will lose 3-4psi just from the tires breaking in.
Also take this into account:
Every 10 degrees colder is 1 less psi
Most tires lose ~1psi per month from normal driving
Also take this into account:
Every 10 degrees colder is 1 less psi
Most tires lose ~1psi per month from normal driving
11-10-2011, 03:27 PM
#9
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11-10-2011, 03:29 PM
#10
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11-10-2011, 03:56 PM
#11
Super Member
It is not uncommon for a tire to lose some pressure over time. Once the temps drop tire pressure will drop about 1 lb. per 10 degrees IIRC. So if you filled your tires when the ambient temp was 80 and it is now 40, it would be expected that you would lose 4 lbs +/-. Always check the pressure when the tire is cold (or driven less than 1 mile).
Took delivery August 1. Temp. aprox. 80. Tire pressure all around was 40 driven - 37 cold (thanks a lot for my sore kidneys, dealer
). Immediately adjusted pressures to 34 cold all around. A few pounds makes a noticable difference in the ride with these low profile UHP tires, it seems. Temp. dropped to the 40's a week or so ago and the TPMS gave a warning. Had 30-31 cold. Re-filled back up to 34 cold.
11-10-2011, 04:16 PM
#12
Super Member
11-10-2011, 06:00 PM
#13
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Hey whats ur mileage per gallon with that diesel?
11-10-2011, 06:50 PM
#14
Senior Member
Fuel economy has been overall around 35-36.
11-11-2011, 09:43 AM
#15
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1953 300 Adenauer, 1971 300 SEL 6.3, 1975 600, 1978 450 6.9
It is not uncommon for a tire to lose some pressure over time. Once the temps drop tire pressure will drop about 1 lb. per 10 degrees IIRC. So if you filled your tires when the ambient temp was 80 and it is now 40, it would be expected that you would lose 4 lbs +/-. Always check the pressure when the tire is cold (or driven less than 1 mile).
Nitrogen is a great scam to suck money out of your wallet and to replace it with air.
Think of it this way. Your tires currently contain 70% nitrogen now. Unless they suck all the air out of your tires in a vacuum, there is remaining air inyour tires so they are really only adding nitrogen to the existing air in your tires.
This is all academic anyway since the advantages of nitrogen are only theoretical and make no difference in the real world. You still have to check your tire pressure every month and you will still need to add pressure periodically.
11-11-2011, 09:38 PM
#17
MBWorld Fanatic!
No, seems just fine and the turn-in is pretty nice. I've not seen them climb above 40. I'm using one of Joe's Racing gauges accurate to 1/10th pound, and they are all pretty on the money for the past 2 weeks, temps have dropped too.
Fuel economy has been overall around 35-36.
Fuel economy has been overall around 35-36.
11-11-2011, 11:49 PM
#18
Super Member
With 1700 miles on my car, since new I have averaged 22 mph and I'm getting 26 mpg. Obviously on the interstate, I get far better mileage, but most of my driving is around town. With my previous 2011 Infiniti M35, I averaged 17.5 mpg so the MB is far more thrifty.
