C300Sport

I have had my car for about 5 months and realized I had gotten really lazy and not checked my tire pressures....TPMS made me kinda lazy I guess. To my surprise, my fronts were 37 psi and my rears were 39 and 40 psi. I know I should have checked them long, long ago but I was amazed MB had put so much air in them. I changed them back to 35 front and 30 rear (33 and 28 recommend) and the car rides much, much smoother. Guess that is what I get for being lazy. I will keep an eye on the MPG and see if it makes a noticeable difference.

Star & Laurel

I think the rear recommendation is higher than that . . . then again not sure what tires you have on your car.

I thought mine was 32 F / 38 R

JimPap

C300Sport,

Drop the pressure to the 33/28 recommended and see life without your teeth jarring loose.

C300Sport

My bad, the recommend is 28 Front and 33 Rear for the 225/45 17 fronts and 245/40 17 rears.

C300Sport

Soo much nicer on the rough sections of my street....can push back my visit to the dentist...

norb

MB ships cars with very high air pressure so that the tires don't flat spot in transit. Its up to the dealer to bring them down to the correct pressure before delivery.

micropower99

On my car it says 30 fronts 35 rears.

JimPap

Somewhat amazing the difference in a few pounds of pressure will do to the ride.

C300Sport

Maybe for the weight of the 4Matic?

micropower99

Possibly, anybody else with 4Matic can confirm this?

delirium

does it matter what size wheels/tires you have on them? I have aftermarket 19's, do i still use the factory recommendations?

aprince2die4

factory AMG 18's 33front/38back on pillar...recieved the car filled at 38front/38back

Distalero

Of course the other thing to consider is whether you checked them cold, or not. Run then much more than a mile and the tire, and air, heats up, reading higher pressures.

C300Sport

Mine were taken stone cold. I am guessing it may be like norb said..transit pressure to keep the tires from flat spotting.

GMW

My tank sticker says 38 front and 38 rear so that's what I've filled.

C300Sport

Yeah, because you have those big wide AMG tires...kinda jealous...

JimPap

Don't the tank PSI refer to driving around with a heavy load?

What does the sticker in the door pillar say?

charliele729

Is 33/ 38 the recomendation for the 18"s AMG rims, I dont really feel comfortable running 39 all around with my C63 rims as the AMG is alot heavier in the front. I am still wondering if it running 28/33 will be too low for 18'.

wishlist

mine are 225/45/R17 on all four wheels.
the recommended pressures according to the sticker is 29fr and 33rr for speeds upto 210kmph with 3 people inside. currently the pressure is set at 30 in all four.
would you think switching to the recommended pressure or going low/high will make the ride even more smoother ?
considering the roads are rough and uneven here in India

JimPap

wishlist,

I made a somewhat lengthy post in another thread about tire presusre.

The first question has to be how many people do you normally ride around with? If you're full load, then use the recommended tire pressure. If it is like myself which is essentially 1 person almost 100% of the time, then go with 27 in front and 31 in rear. Now this is on a 2008 C300 sport (early production) that would tend to loosen your teeth when you hit a bump. Huge difference. The key, regardless of what anyone tells you is to watch your tire wear pattern. If it looks like the tires are wearing more from the centers than the sides, then you know you're over inflated. Conversely, if they're wearing more from the outsides than the center, you're under inflated.

In my case, my car runs quieter and softer than before. My only regret is that it took more over 2 years and 46,000 miles to figure it out.

bigigg

yess it matters..i was told put 40 psi in my 19's.. just check what it says on the side wall.

JimPap

Don't sidewalls typically say the maximum tire pressure which isn't what you normally would run.

Contact the tire manufacturer. They could be helpful. Then post here what you find out.

bigigg

yess it does say max pressure.. i dont fill it up to the max.. i dont recommend that!

coolvi

Never trust the dealer. I did when I took delivery and ended up driving on 40+ all round for 3 months until one of them got punctured.

I've been trying to keep at about 31/36 since. It says 28/33 on the pillar but 30/35 on the gas cover but both agree on the +5 for higher speed/load. Knowing that the speed vs. pressure is a rising curve so based on how fast I could go realistically, I decided that +2 or +3 should be the sweet spot.

Some people underestimate the importance and the degree of impact tire pressure has on ride quality among other things. Afterall, tires are/should be the only contact points to the road which is the main source of effects you're ever going to feel while sitting inside the cabin. For the same reason, I believe that manufacturer's recommended tire pressure levels should be followed for all allowable wheel/tire sizes to maintain the relativity of the body to the road and ride comfort.

Something extra: when I switched to winter tires back in October, I went with nitrogen (because after they messed up my order and the nice manager decided to waive $250 off plus some extra stuff). They did 36 all round at the shop and I had lowered it to 31/35. Relying on TPMS for the most part, I finally measured it last week, and guess what, they're at 31/35 after 4 months of harsh Canadian winter driving! It's almost set 'n' forget! I'm not trying to start the whole 4/5 of the air is nitrogen stuff, but just something from my experience.

JimPap

Here's a pretty good website that IMO tells the true story about running nitrogen in your tires.

http://home.comcast.net/~prestondrak..._tires_FAQ.htm