max90034

I have 2014 GL450 with 19" rims (275/55/r19). The label on the driver side door says that cold tire recommended pressure is 39psi front and 47psi rear. But the gas tank door lebel says 32psi both bront and back. What is the right answer? Thanks.

rmemory

I posted the same question a while back. You can do a search for the thread, but opinions and preferences varied. I feel the most comfortable ride for me is 40 psi front and back.

rmemory

https://mbworld.org/forums/gl-class-...-pressure.html


Here's a link to the thread.

43221B

The label on the door is basically for using the tires in extreme conditions. An example would be if you are loaded with 7 adults + two suitcases behind the third row and driving 130 mph on the autobahn for an hour or more then you should inflate to those pressures. The high pressures keep the tires from overheating under those conditions. Otherwise, as was stated, it is really a matter of preference. The fuel door gives you the minimum. On my 09 X164 with 20" runflats, I got about 40k miles out of my tires which seemed very good compared to what other people using more pressure were getting. From what I understand, adding more pressure will get you more tire wear in the center of your tread and less will give you wear on the outside of your tread (which is what I noticed on my X164). I only have about 100 miles on my 20" Pirellis so I don't know how they will do but I tend to use the lowest pressure possible to achieve a softer ride. So, it's the fuel door for me and I add a little pressure on long trips.

methos1969

I run 32 pounds or it will eat the centers. I've been running oversize/wide/low profile tires on all my cars for years and this is the magic pressure. On super wide tires such as 345's I run 29 pounds. When I get my oil changed I make sure the guys don't add pressure.

SaniDel

Here are the labels from the 'B' Pillar and fuel filler door on a March 2015 GL 550. That's quite a range of tire pressures!

cyclrder

On a 21 inch 550/63 wheel... 39 works best for me. Anything less and you run the risk of damage from potholes...

On 20 inch...you could probably drop down to 37 and be fine.

The problem is that on big temp swing days it can get hot causing the wheel pressure to start off at 39 and end up near 44 and that really is to hard and uncomfortable...

Btw.. The interior sensor seems to run a lb higher than a high quality gauge.

SaniDel

On our first visit to the dealer after taking delivery of our 550 with 21" wheels we had the service department check and adjust the tire pressures. They also advised 39 psi and set the pressure accordingly. The TPMS does display slightly higher pressures, but at least they are all the same. By the end of the day the TPMS typically displays 42 psi in all four tires.

Chedman13

I've been running 38 psi and as another member mentions, it ate the centers up. Centers are 3/32nd and the outer channels are 6/32nd.

I will now be running 32-34 PSI cold. It's such a wide tire this appears to be the best to keep it flat.

I run 38-40 psi on my other cars with more narrow tires to get better gas mileage, but the wear is more even.

cyclrder

you will absolutely run the risk of blowing out and / or bending a 21 inch rim out there with a 40 series tire.. that is just bad advice on the internet.
(I know as I have both bent one wheel and blew a tire with my 22s whilst being careless and letting the pressure get down to 35)

I too have had issues with my old GL550 X164 with the center of the tires wearing in the rear... but I have not seen that with the 166.

Chedman13

I can see you argument. I mentioned it's what I personally do - it wasn't advice, the members can make of it what they wish.

32 PSI is what my authorized MB dealership sets the tire pressure to. It's also on the fuel door.

Each member can make the decision for themselves - higher the PSI, more rim protection, more wear on suspension, stiffer ride, better mileage, less rolling resistance.

Less PSI, less rim protection, less wear on suspension, softer ride, more rolling resistance.

Just don't go below 32 psi cold.

SaniDel

Tires are consumables ... wheels are not. I would prefer to wear out my tires rather than to damage my wheels. If the tires wear too fast or too unevenly that can be mitigated by purchasing tires from a different manufacturer or in different sizes, which can be planned for ... unlike a sudden blowout due to wheel damage. OEM tires are less than $400 each ... what's the cost for a wheel?

http://www.tirerack.com/tires/tires....0&autoModClar=

mist68

Mentioned this under a different subject-we have a 2014 GL550-run 38 psi all round (cold). While in FL, we hit a median at about 30 mph-the left front and rear wheels & tires were destroyed. As the car had 11,000 miles on it, MB required all four tires be replaced. Total cost with alignment just short of $5,000.

No damage to suspension parts and fortunately the airbags didn't deeply. Actually the GL didn't even bounce much.