Bryce1023

I have the 20 inch run flat Coopers on my 2021 GLE 350. I’ve been running them with 38 psi front and 40 psi rear. I find that it is a happy medium for ride comfort and fuel economy. After I had brought my GLE in for it’s A service, I noticed that the dealer brought the tire pressure up to 42 psi. What made me check it, was the ride felt a little too hard. A friend of mine with a BMW SUV told me that he keeps his tire pressure at around 34 psi. I am not sure if there is one correct psi, some of it is how the vehicle feels and reacts during driving in various conditions, some is personal preference. My friend with the BMW said that my tires will show too much wear in the center running them at about 40 psi. Mercedes, although inconsistent in what is recommended, fuel door recommended settings vs driver’s door, doesn’t seem to believe that there is a problem with the higher psi numbers. Just looking for some feedback from other owners and any recommendations would be appreciated. Thanks

Ron.s

Use the fuel door always.

makris0000

Like Ron said, use the fuel door for tire pressure.

I have the 20 inch AMG wheels with Michelin tires and my fuel cap says to do 31 PSI front and back. Last fill up I did was 34 PSI and I noticed the ride was a tad stiffer so I just stick to 31 PSI like my fuel door says. This usually helps with tire wear, fuel efficiency, ride comfort etc.

djer

Also depends on the load too, and yes on the fuel door recommendation. It's much better than the door one since that shows pressure at full capacity which rarely happens.
With that said, I'm running 33psi rear and 35psi front, car is always loaded with 3 toddlers weighing total of 100lbs and most driving is city where lots of intersection and turns, hence the 35psi on the front to compensate for the caster angle turning. Wear has been very uniform across the entire tread, both front and back. There were road trip occasions where we loaded up the car and ran 38psi all around.

And this is on the non run flat 21" Pirelli's

GregW / Oregon

Fuel door chart, amen! I run 32/32 with 21" Pirellis. Your ride must be really stiff!

Frenetic

I always use full pressure. I do this simply because I’m never going to actively adjust my pressure for any given moment; I like the freedom to load up my car at any time without having to worry about inflating tires. And, while it is certainly stiffer, you get slightly better gas mileage, and it provides a margin for natural air pressure loss.

mikapen

​​​​​​The trade-off is reduced impact resistance, center tire wear, and reduced traction.

Use the gas flap pressures, plus or minus a pound or two to suit your preferences.
Then spend 15 minutes at a Discount Tire store every 3 months, and have them check / set the pressure you have chosen. This should be done seasonally at least.
If you want to be ready for weekend loads, and are willing to make the trade offs, have Discount Tire use that pressure when you do your periodic check.

Someday, when you're fiddling around with displays, find your TPMS and set it to the pressures you have chosen. That takes care of your "natural air pressure loss."

Neurobit

Fuel door here also.

abcdef

Thanks to this post, I have now realized that I have been running my tires with way too much pressure. I have a new 2022 GLE 350 with the AMG 21" wheels and Pirelli tires (staggered). I had pressures set according to the tag on the drivers door not realizing that this was for max load capacity. I have now reduced it according to the cold pressure tag on the fuel door. Since when have car manufactures put this additional instruction on the fuel door? My 2016 BMW and 2014 Audi do not have the additional instruction so I use the data on the drivers door for those vehicles.

Ron.s

There are two pressures on the fuel door. One is for two passengers (normal) and the second is for 5 passengers (full load). For most of us, most of the time, the lower setting works best. Maybe it’s info overload, but it does allow for better comfort vs setting them to the maximum all of the time. They ship at max to avoid flat spotting and my Dealer leaves them there.

mikapen

The driver's door post sticker and format is required by the Feds.
The protocol is for the manufacturer to put their findings on the filler cap.
If your Audi and BMW don't have that info on the filler door, read the owners manual. Odds are their info is different from max pressure.

GregW / Oregon

It’s confusing for the consumer. There are two different charts on the B pillar in addition to the one on the fuel flap.

djer

Interesting, the 7-seater with 21" notes max pressure of 38F and 44R on the fuel door flap.

Not really, maybe because I have the extra weight on the back for the seats, now that I thought of it? I feel like higher psi rides more stable when going above 70mph.

abcdef

[QUOTE=djer;8608771]Interesting, the 7-seater with 21" notes max pressure of 38F and 44R on the fuel door flap.


Perhaps the higher max pressures on the fuel door flap for the 7-seater with 21" wheels is because those are run-flat tires? My 5-seater with 21" wheels has the non-run flat tires and the fuel door sticker notes max 31F and 39R.

GregW / Oregon

[QUOTE=abcdef;8608819]That is undoubtedly the case. The seat weight is a non-issue. The higher pressure and stiffer sidewalls have a very negative effect on ride comfort.

HotRodW

If I use the pressure on my fuel door it triggers a low pressure warning. It's comical how difficult Mercedes makes something that should be simple.

mikapen

Go to your Service menu and reset the pressure. You tell the car where you want the pressure setting.
I believe the feds require this reset capability, but I wouldn't swear to it.

Frenetic

I agree.

If you do choose to not use max pressure, be sure to measure and fill when the car is completely “cold.” If you drive to the gas station and fill it up there, in all likelihood, the measured pressure will be artificially high as tires can increase in pressure quite a bit after it’s driven, which means it will be low the next morning.

Best time to check and fill your tire pressure is early morning in the garage after it’s been sitting overnight.

mikapen

If you have trouble setting your TPMS, your Dealer or most tire stores can assist you. It's also in the manual of course.
​​​​​​​It's a good safety skill to master, no matter what Brand you drive.

djer

No, the 7-seater w/ 21" comes with non-run-flats.

HotRodW

I know how to reset it. I've had to do it before.

abcdef

Great that you got the non-run-flats. I assume you have a spare tire?
I was under the impression that for 2022 the third row seat option meant no spare tire and run-flat tires but I could be wrong.

djer

Nope, no spare tire either since the space is taken for the seats. It does come with TIREFIT (the seal + inflator kit).

I believe with the 3rd row option, no spare tire option is available, but as far as installed tires:
- If equipped with 19" or 20", it'll be run-flats and I'm not sure if they give you TIREFIT (I wouldn't think so since it already have runflats)
- With 21", non-run-flat with TIREFIT

djer

BMW's even have pressures for 100+ mph lol I wonder how that passed through the Feds. The iDrive setting can actually store the tire size you're running and give you the recommendation pressures, even down to the ambient temperature at the moment with respect to its pressure.

GregW / Oregon

Wasn’t thinking in my previous post. 21” run flats are available but not in the sizes required for these wheels.