Dealer set my tire inflation pressure to 40 psi
Thread Starter
Junior Member
Joined: Nov 2009
Posts: 52
Likes: 2
2010 C300 4Matic
Dealer set my tire inflation pressure to 40 psi
So I checked my tire pressure for the first time since picking up my car last week. The dealer had the pressure set to 40 PSI. WTF? Why was the pressure set so high? I dropped it down to 36 in the front and 38 in the rear. (Door jamb says it should 30 in the front and 35 in the rear)
Anyone know why the dealer would set the pressures that high? If anything, I would assume that they would have followed whatever the manufacturer stated it should be.
Anyone know why the dealer would set the pressures that high? If anything, I would assume that they would have followed whatever the manufacturer stated it should be.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 5,113
Likes: 57
From: Southwest USA
Another round of ICE
Not sure where you live, but if the car was indoors for a while at the shop and the tires reached ambient temp in the heated garage, he may be allowing for effect of cold weather once you leave. 1 psi per 10 degrees loss. Where and when did you measure the pressure? Is your garage heated? Do you live in a cold weather climate now?
Thread Starter
Junior Member
Joined: Nov 2009
Posts: 52
Likes: 2
2010 C300 4Matic
Not sure where you live, but if the car was indoors for a while at the shop and the tires reached ambient temp in the heated garage, he may be allowing for effect of cold weather once you leave. 1 psi per 10 degrees loss. Where and when did you measure the pressure? Is your garage heated? Do you live in a cold weather climate now?
I think the previous poster may be right. The dealer didn't check the tire pressure before releasing the vehicle to me. No wonder the ride was so harsh. And here I was blaming the OEM Continental tires. Ok, who are we kidding? The OEM tires still suck. LOL.
MBWorld Fanatic!
Joined: Sep 2007
Posts: 1,481
Likes: 2
From: Southeast
2008 C300 Sport, RWD, US
I've also heard that tires are over inflated at the factory so that the tires won't develop a flat spot while in transet. It only takes a few miles for the tires to warm up and for the flat spot to work its way out. But think about it. You get into a car that's been sitting for a few weeks to do a test drive and due to these flat spots it rides like it has a flat. I think they'd rather you get a firm ride than a bad ride.
As far as tire pressures in general, my 2008 model C300 had always ridden too firm for my taste. This is following instructions and using what is thought of as a high end pressure gage. For whatever reason, I under inflated the tires and the ride improved substantially. I may have just gotten a defective tire pressure gage.
As far as tire pressures in general, my 2008 model C300 had always ridden too firm for my taste. This is following instructions and using what is thought of as a high end pressure gage. For whatever reason, I under inflated the tires and the ride improved substantially. I may have just gotten a defective tire pressure gage.
Newbie
Joined: Jun 2009
Posts: 3
Likes: 0
C350
I heard that tire pressure needs to follow the kind of tire being used. If your car is equipped with high performance tire. Their PSI usually needs to be higher than a standard all season tire. There should be a maximum PSI# on the sidewall of the tire. I have a Toyo T1R on my other car and the maximum PSI of 50, so the tire shop usually fills it up around 47psi. They said it will help the tire wear evenly and also give you the maximum traction.
Trending Topics
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Junior Member
Joined: Nov 2009
Posts: 52
Likes: 2
2010 C300 4Matic
I feel it's too low. When I had my tires at 32 all around, the ride felt quite spongy. I currently have it at 38 all around. The ride seems a bit stiff, so I think I'll drop to 36 all around.
Another thing I found out is that all C-Classes list the tire pressure to be 30/35. So whether you have a C250 with 16"s or a C350 with 18"s, you have to run the same inflation pressure? Doesn't make sense to me at all.
I'm hoping 36 will give me a good balance of comfort, handling and fuel economy.
Another thing I found out is that all C-Classes list the tire pressure to be 30/35. So whether you have a C250 with 16"s or a C350 with 18"s, you have to run the same inflation pressure? Doesn't make sense to me at all.
I'm hoping 36 will give me a good balance of comfort, handling and fuel economy.
