huir

i am running 17' tires on my C300. I am currently running with the tire pressure in 28 front 30 rear. Just curious what tire pressure you guys are running on your c300.

zankok

um i run 38 front and 45 rear
its the maximum indicated from the fuel flap

C300Sport

That is pretty crazy high. Are you sure that is what your fuel flap door states? Mine lists 28 front and 33 rear with a note stating that you can run 4psi additional if running above 100 MPH.
Either way, I am sure that makes your ride pretty harsh and you will wear out the center line of your tires long, long before the edges since that high a pressure will have your tires crowned out in the center.

ldtCapitan

I run 29 front 34 rear. Too high and the ride is harsh.

JimPap

huir,

What is recommended on your driver's door sill?

What is your concern... even wear or ride comfort?

How many usually ride in your car?

huir

Ride comfort is my concern. My ride is 28 psi in front and 30 psi in the rears.. What about yours?

kevinwithdabenz

mine is the recommended except for one drivers side rear tire is 38 psi instead of 33

Samieee

30 front 35 rear as stated on driver's door

jon3sh

30 fronts and 34 rear for mine thats what benz shop guys told me but it depends what sizes of tires you have though.

JimPap

Mine is 28 in front and 32 in rear. The door sill sticker on my recommends 28/33.

3 weeks ago at 55,000 miles I replaced my rear Michelin HX MXM4s with identical replacements. Having run them at 33 psi, it was obvious that they had worn a little more in the middle than on the sides. I figured 32 or 31 would provide for better wear. As for ride comfort, I'd think that 31 would ride a little better. This is with the car loaded with 1 person (the driver) most of the time. The heavier the load, the higher the tire pressure.

One of the more interesting things that happened with replacing my original tires with what was suppose to be the same tires is that the new ones road softer. In discussing it on another thread, someone brought out that most car manufacturers have their tire OEMs blend a stiffer tire compound to use on their cars so that they can get a higher MPG rating. So my replacement tires, although are suppose to be identical, in fact isn't. I saw this all to say that if you are experiecing a harder ride than what you would want, it may have a lot to do with the tires and not just the tire pressure.

zankok

ummm I don't understand what is sayz on my fuel flap, there is a few different numbers but i just took the highest, where the set of numbers comes with drawings of 4 men and 5 tyres
I'll try take a picture later, car is at MB right now :/

JimPap

zankok,

Do you usually drive with 4 men? If yes, then the highest numbers.

On your door sill, what does it say?

2008C300AM

My specs are 28/33, and the dealer recommended keeping them 4 lbs over. They lose pressure naturally, so I check them every 3 months and put them back to 32/37. This was after my sensor went off while driving home from San Francisco - beware of this: it's a crazy RED ALERT all over the instrument panel- scared me to death! ... and it was only because they were a pound lower than the specs. You'd think the tire should be blown out to warrant that crazy red alert like that!

omgitsjoe

LOL at the above in ummmmm ....... RED because i've seen this happen a few times with low tire pressure , blown bulb ...... woman driving and applying makeup alerts and yessss it was scaring

JimPap

Angel....check post 10.

Pete7874

That's not how this system typically works. Certain amount of fluctuation (due to seasonal changing ambient temps) is permitted. However, the sensor will go off if one of your tires loses more pressure than all the others. Such is typically the case if you have a puncture or slow leak in one of your tires.

I had this happen when I had a slow air leak from the valve stem area in one of the wheels. It would lose a couple of PSI every week or two, to the point where the difference between this one tire and all the others was big enough to cause the system to post a warning on the dashboard.

The sensor may also go off if for example you calibrated it at say 32/37, but then you get down to 28/33 over time. What you should do in this case is do the calibration while you have 28/33 in your tires, and then add 4 extra lbs afterwards, but do not perform the calibration again. This way, the sensor will probably not bother you until you get down to something like 24/29.

As for the original question, I run mine a couple of PSI above what's recommended on the placard, whatever it is.

haykf1

I found best for me is 31/34, more than that MB reacts too harsh to the road. Interestingly, BMW loves higher pressure and improves handing without sacrificing the ride. Overall, MB suited for more comfort driving than sport and keeping pressure just slightly over recommended works the best for me.

JimPap

I can't help but believe that you car rides rough in part due to the over inflation of the tires.

IMO (in my opinion) it would be better to check your tires once a month (probably only have to add a pound or less) and to air them according to manufacturers recommendations. It'll ride better too.

jon3sh

Right also it depends on your location too lower temp means you will lose air pressure. Winter time in Canada is harsh I always check mine every first week of the month.

Strfry

My gas cap recommends 35 front and 38 back but here in AZ Ill easily add 3-4 more psi all around just driving in the heat. Should I take it down a bit?

zankok

this is my fuel flap...
so is my 38 45 too much ..?? it is quite bumpy though

Pete7874

How often do you drive faster than 130 mph with 5 people and full trunk of gear on board? If not very often, then I'd say your pressure is too high.

JimPap

Would you photograph your gas cap door showing the pressures?

...or is it like zankok's??

If its like zankok's, then the 35/38 is if you're driving 130mph and above with a fully loaded car.

I think zankor's door is saying add 4lbs of psi if you've already warmed up your tires and plan on going 130mp with a fully loaded car. Usually, we check tire pressure when the car has been sitting overnight and use the cold tire pressure. And I've never driven 130mph and with H rated tires, its probably a very bad idea.

2008C300AM

Thanks for your insight Pete! This is exactly the reason I was so scared, I assumed the alert would only go off under a circumstance such as this you detailed below. However this was not the case, mine went off because they were below the calibrated specs. I since did the calibration and have not had that problem again. Thank you again for your reply.

[quote=Pete7874;4204723]That's not how this system typically works. Certain amount of fluctuation (due to seasonal changing ambient temps) is permitted. However, the sensor will go off if one of your tires loses more pressure than all the others. Such is typically the case if you have a puncture or slow leak in one of your tires.

2008C300AM

Thanks Jim, I did read over that when you posted it. I'm still on my original tires at 15K miles. I think I will lower the pressure some, it does drive a little rough, but I came from a bmw 740IL, so everything feels rough after that! This is such a great forum! I am learning so many little details!! Thanks!!