what is the right psi for my ML350? I got a warming sign this morning, both my front tire is 38 psi, and both my back is 42. Are these correct? should I adjust both my front to 42 psi? thank you.

 

You can refer the tire pressure chart on the inside of your fuel filler flap.

 

Once you change the pressure, you may need to reset the default tire pressure to the "current" one. I believe your TMPS will trigger when pressure drops from whatever the "default" setting is.

 

I run 35 cold 39 hot. You must reset the TPMS after any change in tire pressure.

Beware over inflating cold tires. Hot tire pressures can be up to 6 lbs higher. Also over inflated tires are rock hard for your comfort.

 

I am afraid that under-inflating your tires is much more dangerous that slightly over-inflating. The pressures listed on the fuel filler door and/or the driver door jamb are COLD pressures. While you may get a somewhat harsher ride with over-inflated tires, it's under-inflated tires that result in blowouts and rollovers at speed... remember the Ford Explorer & Firestone fiasco?

I don't know what the recommended tire inflation pressure is for your vehicle and tires (and changing the tire diameter BTW also changes the inflation pressure), but 35 psi seems awfully low.

 

I have 2014 BT ML and sticker shows 35psi for all 4.

 

On the OEM 19" wheels & tires, a light load and low speeds (< 100 mph), 35 psi is possibly the allowable minimum. With 20" wheels and/or higher loads and/or 100 mph cruising, you'd need to raise the pressures accordingly.

 

Car came with OEM 20' wheels & tires
265/45R20. And MB attached the sticker.
So what will be the optimal cold tire pressure?
Normal load and <100 mph.

 

I run mine at 40 psi cold all around for normal driving,and up from there (especially the rears) if you're going to load up the car to pressures indicated on the door jamb (B pillar) -- 45 F & 48 R cold.

 

Don't you think 48 cold is a dangerous pressure for the tyre integrity itself. That's 3.3 bar, which means you'll go up to 3.5-3.7 according to the speed/temperature/style of driving. I don't know what's the maximum pressure safe for a certain tyre but over 3.0 bar sounds too much, maybe I'm wrong. I run mine around 37-38 psi cold usually, which goes to 40psi warm, on 20'' rims.

 

My ML came with XL tires (extra load), and I replaced with the same. Max cold pressure is 50 psi. I keep mine at 40 front and usually 42 to 45 rear.

Keep in mind we have a heavy vehicle and XL tires are meant to have more pressure. XL tires don't reach their max capacity until they have 41 psi.

 

Absolutely not. It is the air in the tire that carries the load. Gasses are compressible and without enough air in the tires, the tire sidewalls will deform way too much and compromise the structural integrity of the tire itself. When my SUV is loaded and I am towing the race car trailer, I most certainly inflate them to 45psi F & 48psi R cold. Max operating cold tire pressure indicated on the tires themselves is 51psi. The spare (which is a narrower tire) should be inflated to 60psi in order to support the weight of the vehicle.

 

I found the following from the MB site.
http://mercedes-benz.custhelp.com/ci...0pressures.pdf