MB-BOB

Then for you, inflating them to 32psi means that they are 36% underinflated. I would recommend at least 45psi for the 17in. Potenzas. Forget about what the door placard says completely.

Keep in mind:
1) You will seldom, if ever, drive the car at it's fully loaded GVW. The 50psi maximum is intended for full load. And Bridgestone builds in some margin above 50psi for liability reasons. So, inflating them to 45+ leaves plenty of margin and will do no harm at all.
2) Racing tires run at lower pressures because they are designed for maximum grip at lower pressures, and are not intended to last 40,000-70,000 miles. These are NOT racing tires. Running them at lower pressures will only ensure that you buy new tires sooner.
3) Higher pressures result in better gas mileage and even tread wear.
4) You will notice no appreciable difference in ride quality, or handling.

My car before the C320 was a Ford Probe GT 5spd. It came with Goodyear Eagle GT Gatorbacks in 225x50R17, not known as a mileage tire. The max pressure for this tire is 44psi. I kept them at 42psi all the time, and I replaced them at... 58,000 miles. And I didn't baby them either. I threw this car around like a rag doll, and it performed quite well at these pressures. Ride was a bit harsher in the Probe, but the ride is not affected in the more refined suspension in the Mercedes, I can assure you.

The auto broker from whom I bought my Mercedes advises all his customers to run tires at their MAX allowed pressure for best efficiency and longevity.

vdubpower

isnt there a greater chance of them bursting at higher pressures, especially if u hit a nasty pothole?

nlpamg

I inflate them "warm" (after driving it for like 15 miles) at 39.5 at the rears and 35.5 for the fronts.

My OEM PS are still pretty good at 18k miles.

BTW, I had a loaner 05 C230WZ with the Continental ContiSports and they SUCKED! My PS were WAAAAAAY better than the Continentals in terms of cornering, handling, and noise. The Continentals seemed more comfortable, but not close to being as sporty as the PS.

Buellwinkle

It all depends on the type of driving you do. If you are mostly on the interstate, inflate them to the low to mid 30's. If you do slaloms at the race track or around town, you want to be closer to the 50psi for better handling. There is a trade-off in ride and wear. I can't believe if you run your tires at 50psi you will have that good a ride and on highway driving you will wear out your center first. The 50psi max is for certain conditions and loads, it's not intended to be the recomended tire pressure. The tire shop by me put in 45psi on new tires and the car rode like poo, felt every expansion joint and groove on the road.

Outland

50 is too much for normal everyday driving. On a manual car, or one with considerably more power than the weezy 240 or 1.8L 230, this translates into more oversteer when you get on the gas around turns. Then there's the teeth rattling hits you take from tires inflated that high. I run 35 front, 40 rear. I like a little oversteer.

Outland

My wife had one of these when we got married. I think it had a smoother ride than the benz, but didn't handle as well. Great exhaust note though!

SCFALIA

I got Toyo Proxes T1-R's 225/40/18 (front) and 255/35/18 (rear). the tires have a max psi of 50 and the person who installed it for me recommended I use the max 50 in the rear and 45 in the fronts. it should be way different for stock but I figure I let you guys know what I use for diversity reasons

PsssTkiD

i still dont get it, why would mercedes recommend something 28 @ 32 on 205/55/16 (with max of 51psi) if it's under inflated? .. pls help . ty

diamondblak05

I usually pump mine with 35psi for the fronts and 32psi for the rears. After it warms up, it'll be like 37-38psi fronts and 34-35psi rears....for me, this feels the best. Smooth ride while not sacrificing too much in the handling department. 40+ psi and I can feel every little bumps, imperfections, cracks, etc...on the road.

PsssTkiD

how come u have higher PSI in the front than rear?. then MB placard has higher PSI in the reaR?

advans

29.5-30psi front, 33.5-34psi rear...this is what i have on the double spoke 209s, on the stock 17" 7 spokes, i advise u to just put 29/33

diamondblak05

Because the front weighs more than the rear.

Tishers

Right On.

jdetar

Be careful with some of the advice here, there's a lot of hearsay and opinions. Choosing a pressure does result in some opinion but here are the facts:

1) If you're running stock tires/wheels the MFG knows best and placed those pressures there for the "happy medium" between handling, comfort, tire wear, and safety.
2) If you're not running stock tires and wheels it does totally depend on your tire compound, sidewall, and size to figure out a proper pressure. Ie: for my 19s w/ Nitto 555s I run 41 PSI cold. Or for my 18s on my Corvette w/ Nitto 555 RII's (they have a much stiffer sidewall and a softer R compound (100 tread wear)) I run 32 PSI cold to achieve this. And with my MT ET Street's for drag racing I run 10 PSI cold. On my 3/4 ton truck I run 45 PSI cold. So as you can see every tire and it's purpose does vary.

The general rule of thumb for STREET tires is this. Inflate your tires at least to the point where you do NOT roll onto your sidewall. Most tires have a little triangle/arrow at the end of the tread meeting the sidewall which points to the spot where you want to be. If you're rolling past the triangle, add air, if you're not getting near it you can take some out. This of course is assuming you test drive and corner hard enough to tell this. If your tires do not have the triangle then follow the same guideline of not allowing the tire to run onto the bare sidewall.

Once you have found this spot you would then want to look at the tires on a flat surface while on the car and see if the tread is flat and all on the ground, or if it's rounded and you're not riding on your whole tire. For every day street driving you do not want this to happen as it will prematurely wear. Also once you have achieved the final result make sure the pressure is within the tire boundaries listed on the sidewall. Ie: if a tire says max pressure is 40, don't ride around with 50.

PsssTkiD

i have pirelli p.zero.nero M+S now. used to have MXV4 plus (stock i believe). both have max of 51 psi. since i was running the stock before, it was on 28/32 as it says on the side panel. it looked a lil flat especially in the front. now, i just have it on 32/35 and it looks a lil bit better. but ill check the triangle you are talking about. ty

C43AMG

Sounds like we need Luke from Tire Rack to chime in on this topic.

Saprissa

Problem with that, though, is that STOCK Tires are different from dealership to dealership.
Just in this thread alone, we have Continentals, Michelin PS, and Pirellis.
Then you can delve into the different types of Conti's, Michelins and Pirellis that each dealer or MBUSA chooses to outfit their MBs with.

So as MB-BOB has repeatedly said:




Carlos

Saprissa@aol.com
Click here to see the:
Irvine, CA - Oct 15th Oktoberfest MB Meet attendee list

jdetar

Carlos,

Ahhh! I'm too new to MB to realize that. Every other car I got there were only one or two tire options. "summer and all season" they would say. But figuring that is the case OK.

However, I disagree very much with "what the tire wants". Because the tire has no idea what vehicle it's going on, how much it weighs, and what kind of driving style you will be doing. The TRUE general rule of thumb is what I posted in regards to figuring out your best pressure. That is how we were all taught to do it here from the pro's.

MB-BOB

When I say give the tire what it wants, I mean that you should consult the tire sidewall inflation values and be guided accordingly. The door inflation placard is a "One size fits all" recommendation, but as Carlos and I and others have tried to point out, the stock tires supplied by MB VARIES ALL OVER THE LOT, depending not only on which size tire is installed at the factory, (which varies from model to model) but also which brand of tire, with as many inflation variables. The inflation placard doesn't even begin to account for the differences, but is the same on every car.

In any given year of production, MB gets their tires from three different manufacturers. In 2001-2002 it was Continentals, Goodyear GA, and Pirelli P6, for standard sedan fitment. Nowadays it's Continentals, Michelin PS, and Pirellis. MB buys these tires based on the best deals they can get from suppliers, and I obviously doubt they even research what tire pressures are recommended on the tires they buy in bulk.

The standard P6 Pirellis that came on my car were nearly SHOT in less than 20,000 miles, because I stupidly inflated them per the placard, but the tires themselves were 51psi tires. (The dealer even refused to rotate them per B Service guidelines, because they said they were worn out and unsafe.) Once I rotated them myself and bumped the pressure to 46psi, the wear stopped completely, and I nursed another 7,000 miles from them. Handling and ride was no different at all from the lesser pressure settings.

I have never seen a door inflation placard on any car I've purchased (Ford, Chrysler, GM, Honda, Toyota, Nissan, Mazda, and now Mercedes) where the inflation placard matched the inflation ranges on the actual tires supplied with the car.

If I told you to microwave all Lasagna TV dinners for 30 minutes at 425 degrees, would you do so? Of course not. You would read the instructions on the TV dinner container and use the setting prescribed. All I am suggesting is that you do the same with tires, reading the settings prescribed on the tire sidewall. The tire manufacturer knows better than MB how their tires are manufactured, the performance envelopes designed into the tires, and what inflations standards will give the best results with that tire.

Do what you want guys. Just offering some opinions to debunk some old wives-tales, based on experience.

drexappeal

Just looked at my stock Pilot Sports (Michelin) and the MAX PSI indicated is 51, so I adjusted (especially because I'm trying to conserve these for as long as possible, until I can afford my rims).

I adjusted to 41 front, 45 rear. I inflated when they were cold, so that's why I went lower than MAX. What you all think?

I've run on these tires for about 20,000 already and trying to make them last until after Christmas. Think it'll work?

C43AMG

I hate threads like this.Everyone here makes valid points for their how much their tire is inflated and why.I wish we could get a EXPERT to chime in on this topic .No disrespect intended to anyone who posted here.

jdetar

Even various "experts" are going to have opinions. I would say my guidelines on tire pressures are excellent without hesitation because I've been doing it that way for a very long time, and I compete in various types of racing (roadracing, autocross, drag, and formerly motorcross). My guideline though is exactly that, a guideline. To obtain the perfect tire pressure you would have to take it several steps further to determine what is the best for your driving situation and tolerances. Because each and every scenario and purpose will differ just as I stated above. Ie: I played around with 9-14 PSI on my drag setup for a long time before I found the perfect 10 or 10.5 depending upon conditions. I played around with roadracing before I found the perfect 32 on my current setup, and my benz w/ 41, etc.

Those numbers would also change with the tire, tire/wheel size ratio, conditions, and alignment.

drexappeal

I know exactly what you're saying C43AMG. It really makes a difference when there is someone who is a "expert" in a certain field to chime in and explain why certain things would work to a particular advantage.

All my information is based on knowledge passed on to me and from personal experience. I'm sure it's tough for "experts" to chime in, just based on how often new threads pop up and of the experts that are on these boards, do they spend free time on the boards at all.

Either way, I think that one very good point that was made on this thread was with regards to what the MAX psi is on the tires and that should be the standard for how much psi to use instead of the recommended listed in the gas tank lid.

il_dirigente

So one dealership said I had bent rims, I take it to another mercedes dealership and they said that my tires were at a high psi level: 40. So they changed ALL of my tired to 32 (when it says front 28, rear 32, ironic, no?)

The main problem was my car shimmied/shook a bit. So now, I must admit, it is better since they 'changed the tire pressure' but instead of feeling it in the steering wheel, i feel it in my seat, which means the problem is in the back now.. right?

HAs ANYONE heard of the pressure in the tires thing? Because when i heard that i just could not believe it, i thought that was such bs.

What do y'all think?

TruTaing

I could understand how over inflated tires could cause a bumpier ride.... but.... how does one place say you have bent rims, and the other say you have over inflated tires? When i got my car (used) the tires were over inflated and the ride was quiet a bit rougher. I bought a little tire pressure gauge, fixed the tire pressure accordingly (28 in the front and 32 in the back) and my ride was quiet a bit smoother.

I think you should explain your "problem" a little better here and clarify upon: "pressure in the tires thing?"

-j0hn