2017 e300 Sedan - Correct tire pressure?
I have a 2017 e300 sedan, sport, with 19" AMG Rims, and 245/40R19 Continental Pro Contact Gx SSR MOE tires.
The b pillar shows 37 psi front 43 psi rear for those tires. The fuel filler cap shows 33 psi all around. The owners manual says look at the b pillar and fuel filler cap.
The car came from the dealer 35 front 37 rear. Called the dealer, no clue.
Any help would be great.
Thanks
Last edited by frankj9000; Jan 12, 2017 at 10:43 PM. Reason: Misspelling
Here is the bottom line. For normal, general purpose driving use the gas filler cap recommended psi. For autobahn type driving (fast and long) or heavy load or towing, use the psi on the pillar. Having said that, you may want to adjust a pound or two for size and type of tire and/or individual ride and comfort.
Here is an article that explains it better: http://www.tirerack.com/tires/tirete....jsp?techid=72
http://static1.1.sqspcdn.com/static/...+inflation.pdf
You can see from this table that the lower profile tires do need to be run at higher pressure in order to carry the load.
For that load on tire and speed is important.
On the car is advice that high that its impossible to be to low pressure in any condition people are able to use the car, for responcibility reasons .
In the book of car is a more reasonable advice .
I am able to calculate it for you if you give 100% acurate determined loads on seperate tires , and maximum speed you wont go over for even a minute.
This is impossible , so we always have to use as much possible reserve.
To much reserve though gives that less deflection that comfort and gripp get unaceptable, so we have to find the right balance .
But to low pressure gives tiredamage , and can cource in the short or long run blowing tire and accidents with the missery that goes with it.
And so pressure should never be to low, better to high with discomfort then to low with chanche on accident.
Greatings from a Pigheaded Dutch Selfdeclared Tirepressure-Specialist.
Peter
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For my everyday driving in the US with very little cargo and at max 2 passengers 99% of the time, the gas cap is sufficient for the best ride according to Mercedes. But I go 35 / 35 to make sure at cold the tires do not rest below 33 / 33
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I use the gas tank pressure plus 10%: 33/33 normal load: 35/40 maximum load: I have stock 18 inch wheels on my E450. Most of my driving is myself or with my wife, or myself and my ski gear so I am always less than 5 people so I use 33/33 plus 10% 36/36.
I find that 10% plus, at cold, i.e., sitting overnight, gives me better handling, better fuel economy and the ride is still silky smooth.
Note that a drop or of even 10 degrees will change the tire pressure 2 or 3 lbs. So in the fall and winter I have to add air to keep the pressure at 36/36.
I have air compressor at home and a digital tire gauge. BTW, the pressure reading on the information screen is withing one pound of my digital gauge which confirms it is accurate.
I use the gas tank pressure plus 10%: 33/33 normal load: 35/40 maximum load: I have stock 18 inch wheels on my E450. Most of my driving is myself or with my wife, or myself and my ski gear so I am always less than 5 people so I use 33/33 plus 10% 36/36.
I find that 10% plus, at cold, i.e., sitting overnight, gives me better handling, better fuel economy and the ride is still silky smooth.
Note that a drop or of even 10 degrees will change the tire pressure 2 or 3 lbs. So in the fall and winter I have to add air to keep the pressure at 36/36.
I have air compressor at home and a digital tire gauge. BTW, the pressure reading on the information screen is withing one pound of my digital gauge which confirms it is accurate.




Do not know about whether or not 19 inch wheels need higher pressure.
What does the recommended pressure on the fuel tank say - more or less than what it says on my car with 18 inch wheels?
Use that as a guide.




I examine the sidewall of the actual tire. It will have the maximum, fully loaded pressure recommended for the tire from the tire manufacturer. Whatever that value is, I subtract 10-15% and fill to that pressure.




Assuming 50 pounds less 10-15% and you get 42-45 psi. I would /not/ go with that.
The wider the tire, the more pressure is needed to keep the center tread inflated and even out the treadwear. This is not rocket science.
I've observed the tire sidewall PSI less 15% for many years, and I get the most even treadwear with zero problems. The ride is less dull... still smooth but more lively, I'd describe it. Better fuel mileage, too. YMMV
Last edited by DFWdude; Sep 20, 2019 at 07:32 AM.




Inflating to maximum 51 psi less 10 to 15% imo, may not be the most prudent thing to do. (personally I think it is a dumb idea)..
10% to 15% less than 51 psi would be 44 to 46 psi. Not only would the ride be rock hard your tires would wear unevenly: the center would wear out way before the sides. Your contact patch would also be diminished and in rain when braking that could be fatal. You also increase the risk of a blowout and bent rims.
Also in warm climates when you drive at high speed you can expect the pressure in your tire to go up by 6 to 8 psi. When that happens you would be exceeding the maximum psi on your tires which would be dangerous.
As I posted, I use the tire pressure recommended on the fuel flap, 33 psi (normal load) plus 10%, 36 psi. The ride is still silky smooth, the handling more precise and both tread wear and fuel economy are improved.
For detailed analysis about the dangers of over inflating tires see: https://blog.firestonecompleteautoca...ate-car-tires/




As noted previously, Tire Manufacturers know what is best for their tires... better than any car manufacturer. And Mercedes-Benz wants it's customers coddled in comfort, so a $1200 set of tires every 18-24 months is no consideration on an $80,000 car.
Last edited by DFWdude; Sep 20, 2019 at 07:39 AM.
Inflating to maximum 51 psi less 10 to 15% imo, may not be the most prudent thing to do. (personally I think it is a dumb idea)..
10% to 15% less than 51 psi would be 44 to 46 psi. Not only would the ride be rock hard your tires would wear unevenly: the center would wear out way before the sides. Your contact patch would also be diminished and in rain when braking that could be fatal. You also increase the risk of a blowout and bent rims.
Also in warm climates when you drive at high speed you can expect the pressure in your tire to go up by 6 to 8 psi. When that happens you would be exceeding the maximum psi on your tires which would be dangerous.
As I posted, I use the tire pressure recommended on the fuel flap, 33 psi (normal load) plus 10%, 36 psi. The ride is still silky smooth, the handling more precise and both tread wear and fuel economy are improved.
For detailed analysis about the dangers of over inflating tires see: https://blog.firestonecompleteautoca...ate-car-tires/




That is why I posted that starting with 44/46 psi would be dangerous.




I've put 9,000 miles on some new Conti Contacts, and the treadwear depth measurements are identical -- groove to groove -- across the entire tread patch. You will NOT get that on Contis inflated only to 32psi cold. Take it to the bank.
Most MB "owners" don't care, because they will return their "rented" car after 2 years, only to be zapped the cost of new tires because the old set wore unevenly.
Last edited by DFWdude; Sep 20, 2019 at 07:56 AM.




If you start at 44/46 psi cold (10% to 15% less than max 51 psi) after driving an hour on the interstate when the ambient temperature is 85 degrees or higher, the temperature in the tires will be above 115 degrees and the psi will increase by 6 to 8 resulting in a psi above 51 the maximum. This will be dangerous.
Your ride at 44/46 psi will be rock hard, and the chances for a blowout or rim damage will be increased. At this high pressure there is little to no give in the sidewalls: hence the rock hard ride and increased potential for blowouts and rim damage.
But the real problem, regardless of what you say, is that your contact area at 44/46 psi will be diminished and in the rain when braking the results can be disastrous
I have an accurate tire gauge and periodically check my tires for wear: at 36 psi my tires, front and back wear evenly, across the tread and I usually get between 35,000 and 40,000 miles tread life.





