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Hello guys I’m new to the MB world and this is the first MB I’ve owned so please bare with me if I don’t make any sense. I’m trying to get the kPa even on all four tires. I have a 2015 C250d AMG Line Premium Plus with 19in Rims. The recommended kPa on the fuel cap says kPa 250 I convert that into Psi which is 36 Psi. So when I put in 36 Psi in all four tires cold it’s still never even on the Tire Pressure Monitor in the car and that’s also normally the case when hot. Is there any tips on how to try keep them slightly even? Many Thanks
I've noticed on many of my cars with the TPMS readout that when the car sits the tire temps can vary based on the sun hitting them, breezes, etc. The temp variations can definitely affect tire pressures fairly significantly. The best reading is achieved after driving the car a while at a constant speed such as a highway. I had a pretty long highway commute to work each day and after about 10 miles or so the pressure readouts stabilized. I made a mental note of which tire was high or low and adjusted accordingly. Also the sensors themselves are not as accurate as a high end pressure gauge. When the car sits a while the readings can be slightly different, but once you run the car for a period they will all get up to the same temp. If you have an alignment issue you may see one running hotter than the rest, assuming all four were set perfectly with a good pressure guage. It's interesting to see how temp fluctuations affect the tire pressure. As an example, notice the tire pressure after a long highway run on a hot dry day - if you run into a rainstorm the pressure will drop a few pounds when the rain cools the tire. Hope this helps. OCD I'm not LOL.
It is good to see people actively checking tire pressures, however you are taking things to the extreme. Get a good tire pressure gauge and check your tires once a month or whenever you feel like it. Mercedes recommends at least once every 3 months. This is the reason why Mercedes started removing the actual tire pressure readouts from the instrument cluster. Unless you are in a racecar where tire pressures need to be at specific levels for proper grip and speed, or if you have leaking tire pressures, then you are worrying too much about nothing.
There are many things that can affect the sensors, and in the end they are there to help you (unless the sensor is failing). Check and correct your tire pressures as often as you'd like but enjoy driving the car and don't worry about a 1 or 2 psi difference from tire to tire.
Attempting to get all four tires to an identical pressure will most likely require several attempts, that's assuming its doable, especially when taking into account the gauge error tolerance. But expecting pressure to remain identical is unrealistic. Simply backing your vehicle from the garage to the driveway, say, on a sunny day, will almost always result in change in the exact pressure so painstaking achieved. Changes in outside air temp, will affect pressure. In general, a 10 degree temp. swing results in a one psi change in tire pressure.
Check and set tire pressure e.g.,32 psi, first thing in the morning prior to driving the vehicle.
Dealers set them at 40 so people don't come back for months for a low pressure light. With runflats in Pennsylvania you might as well fill the tires with cement. I run 32 rear 34 front Cold and its a pretty good balance- Oh it's no S Class ride for sure with the steel AMG springs, but with the radio on to drown out door wind noise and up to now my clattering engine-it was ok with those pressures. Unless your carrying 5 passengers and luggage and I guess a homegrown spare tire-since it doesn't come with one- this seems to work for me
02-16-2018, 09:28 AM
