The fuel cap door tire pressure chart for my 95E300D states 27 psi for front and rear "normal load" and 28 front 33 rear for "maximum load".

Is 4 adults considered maximum load?

27 psi seems low.

I would look on your tires, what ever pressure it says on your tires. That is what I do.

The pressures on the fuel door are the best for the original tire size. The sidewall shows maximum tire pressure and load ratings.

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Gone to the dark side

- Jeff

That is what the hypermilers do to get the lowest safe rolling resistance of the tire to maximize fuel mileage, but it's an uncomfortable ride at best.

MB recommends a pressure that considers both a comfortable ride and good handling response. Max load is considered four adults and their luggage.

I think you should experiment with slightly higher pressures to find what you like. For my E300 Diesel, I like 32 psi for all four tires.

Different brand and design tires give different ride/response also, not all will ride well at 27psi or poorly at 32psi. The front/rear balance is maintained by the differential between the front and rear tire pressures typically, anyone who does any racing will tell you that the best handling tire pressures are usually a result of experimentation. Also, I don't remember if it is still common, but the '80s/'90s cars used to have a note in the filler lid to add 10psi for speeds over 100mph, ...

And yes, the higher the tire (air) pressure, typically the lower rolling resistance and resultant fuel mileage but often at the expense of tire wear, ride quality, and sometimes traction.

__________________

Gone to the dark side

- Jeff

I've had great success with running at 32psi all around on my last 300SE. Comfort and handling are good, and I got 51K miles on my last set of Toyo's with regular rotation.

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Marc Galassini

'93 300CE 38K Sold
'89 560SL 19K Sold
'91 300SE 191K Totalled 11/6/08
'90 300SE 90K

I play around with tire pressures on my vehicles until I find a pressure I like. The factory recommendations for Mercedes are low and result in mushy handling in my opinion. I like to run 32 at all four corners in my 300D and 250, and I keep the 240D at 36 to cut the rolling resistance down some. It needs all the help it can get.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

I go a bit softer and run 30 psi in mine. The car soaks up bumps like a magic carpet at 27psi but handling is a bit mushy. I tried 32 for a while but it seemed a bit harsh. The best advise I guess, is to experiment a bit and see what feels best for you.

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"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

That is the same as my 1992 300D.

I usually aim at 27.5 front, 30.5 rear at the monthly average temperature at weather.com. I adjust tire pressure every month. I also measure the ambient temperature when I do the adjustment, and use the compensation: 0.5 PSI / 6 degrees F (this is in the MB owner's manual).

You also need to follow the MB recommended tire load index.
Many 195/65 15 tires have load indIt ex 89. They are not for your MB. The tires for your car should have load index 91.

"Is 4 adults considered maximum load?"
I think it depends on the weight of the people. The weight of four heavy people can be close or even above 800 lbs, where many passenger car model's maximum load capacity is about 850 lbs.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.