Jinzen

Whats your door jamb say for the correct tire pressures on the car?

I was surprised to see F/R 40/44 PSI for my C300 4Matic (luxury).

Dealer set the pressure to 38 all around when I got the car.

floridadriver

That sounds a little high for such a tire size for a smaller sedan. I am no tire guru and don't know the exact tires on your car, 1356lb/ tire max load at 51psi is what conti tire shows on tire rack dot com for the conti moe(run flat). I'd think less would fly for the low vehicles weight. I'll see if I can dig up a. Load chart online.

I saw some at dealer with Perelli tires too.

How do you like the ride at those pressures? Feel any difference? Also, if you have airmatic may be different. Enjoy the car! I like the luxury styling of the C!

StanNH

My standard C300, with the 18" tires, says 39/45 psi on the door label.

c4004matic

The tires are runflats so I would not be surprised. However MB is notorious for getting the tire pressure labels wrong. since they sell the cars in so many markets. Consumer reports had the issue that the door label said one thing while another label elsewhere (I think in the gas door) said something else!

Jinzen

My gas door doesn't have any tire pressure readings.

c4004matic

That a good start, just one label! Check the owners manual and see if they match.

floridadriver

I can't imagine that MB would have the sticker or manual wrong.

I haven't been able to find the load chart for the tires online. But based on those numbers, at 51psi, 4 tires should carry 5424Lbs. On a log rhythmic WAG, I can't picture it needing mid 40s. It also seems odd (again, I'm not a tire expert) that the rear wheels would be significantly higher, especially on a front heavy AWD. Somebody here probably can chime in with more expertise than I. (Or the MB book/sticker)

Another question for those with a new C, or experience with run flats, does the change in tire pressure change the ride as much as a traditional tire?

Glyn M Ruck

Tyre pressures on labels are nothing but an estimate for a specific tyre construction & assumed load. Set tyre pressures for your own conditions & tyre brand preference. Monitor wear & adjust accordingly. Center of tread wear = over inflation, shoulder wear = under inflation. Set pressure for even wear in your circumstances.

Increase pressure for long trips to prevent pressure build up due to heat.

benzw205

Yes but how to choose what is good for us ?

benzw205

Hello,

Do you know if run flat tires pressure should be higher than standard tires ?

Thank you.

Glyn M Ruck

A good starting point is 2.3 to 2.4bar all round for conventional tyres. In my experience Benz rear pressure recommendations are too high for even wear unloaded one up.

I have no experience of run flat pressures other than what is shown on many threads here.

There are so many conflicting views even between tyre companies.

RF's should only be used with TPMS. On this they all agree.

BTW ~ Some RF's do not show the typical over/under inflation wear patterns we are accustomed to with conventional tyres because the tread strata is firmer & deforms less.

Merlin1

it does state in the manual that pressures except AMG can be reduced by 4PSI without affecting safety

floridadriver

Just curious if anyone else with a 2015 C with the tire pressure label on the gas door as mentions in manual? I know Stan said he didn't, in another post someone mentioned they did, but didn't mention the pressures listed or if conflicted with ones door jam. As I recall, MB allows lower pressure for lower speeds or loading on the label.

bacardi73

I used the gas door and have all 4 at 36PSI as it state's for "normal load". Below that it states almost exact same thing as door jam. 39PSI front and 45PSI back at "maximum load" and speeds over 100mph. Gas door doesn't specify maximum load (unless I missed it) but door jam shows 794lbs as max load or weight.

gocal73

Did lowering the PSI improve ride or handling? Mine came for the dealer at 4 different pressures, all over 41. I hate run flat tires and hope lower tire pressure might help.
Thanks.

bacardi73

Unfortunately not really. Did you get the Sport too?

bacardi73

Here is the pick of my door jam PSI's and gas door PSI's.

bacardi73

Oops I misquoted the door by stating "speeds over 100mph". So "For driving less than 100mph" -4 psi....does that mean I can reduce my current 36psi to 32psi all around? And what 's considered a "normal load" anyhow?

mihaelb

hmm...doesn't 360kg max load sound kind of low? put 4 big guys in the car, and you can easily reach that, without cargo...

also, the second image doesn't specify tire size. Should it not differ for different tire sizes? Interesting, too, that it suggests -4psi for speeds below 100mph. Never seen that before

PeteInGilroy

That was my first thought...you could run 32 psi all around, based on the fuel door label.

vsnlweb

Normal load I would assume that you are doing everyday driving running normal errands and going to work. You would usually have around 2-3 people in your car and maybe a few items. Your trunk wont be full.

Honestly I would stick with 38 psi. Even tho they are run flats and would not wear the same, it should not do any damage, or wear unevenly. Most tires are rated to be inflated to 50 psi, but no one ever reaches any where near that. Plus 38 is great for cold weather. Which I am in.

PeteInGilroy

But I think he is trying to get a softer ride.

bacardi73

mihaelb - I believe my previous BMW 328i stated same thing about the "speeds below 100mph" and i think it showed a "- psi" too but can't remember amount. It was either on it's door jam or manual. Either way I didn't follow it as the comfort level of ride didn't bother me like it does now. So only reason I'm asking about the psi difference is because the ride on the C300 Sport seems overly harsh. Not that the psi diff will be night and day

bacardi73

Correct...if possible

floridadriver

Thanks a lot for the pics...

I'm in the car alone most of the time, and <100mph. Based on the photos, I'd probably run 32/35 (based on the cars sometime feeling the back disconnected if same pressure) and then watch for wear closely as Glyn discussed above and adjust accordingly. It won't be night and day for you for smoothness, but it is a start. Not sure if could work a swap to standard 17" wheels, that would probably be only other cost effective measure w/o getting into swapping to the Luxury package springs/shocks. BTW, I can understand, here many roads are flat concrete with expansion joints which have been patched with asphalt. Sportier suspensions are a punishment on them, and not really any curvy roads in the state to utilize the stiffer handling.

You may need to reset the TPMS in the settings menu. Please let us know what you go with and if some positive results.