Why is tire pressure so different front 2 back?
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 74
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From: League City, Texas
2008 Mercedes Benz E550 AMG Sport Package
Why is tire pressure so different front 2 back?
I just checked my tire pressures and was reminded how varied the tire pressures are front to back. My E550 runs 29psi in front, 35psi in the back. Not used to seeing staggered air pressure in a RWD vehicles.
Any ideas? Just curious.
Any ideas? Just curious.
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Joined: Feb 2009
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From: North Carolina
2014 E-350W4
I can only imagine that, the lower air pressure in the front contributes to a smoother ride and the higher rear air pressure supports additonal weight from passengers and a loaded trunk? My 03 E320 is Frt 26 PSI and Rear 32 PSI.
If you equalize to the higher pressure, you may get slighlty better MPG but I think the ride comfort may suffer a bit.
If you equalize to the higher pressure, you may get slighlty better MPG but I think the ride comfort may suffer a bit.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 74
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From: League City, Texas
2008 Mercedes Benz E550 AMG Sport Package
I can only imagine that, the lower air pressure in the front contributes to a smoother ride and the higher rear air pressure supports additonal weight from passengers and a loaded trunk? My 03 E320 is Frt 26 PSI and Rear 32 PSI.
If you equalize to the higher pressure, you may get slighlty better MPG but I think the ride comfort may suffer a bit.
If you equalize to the higher pressure, you may get slighlty better MPG but I think the ride comfort may suffer a bit.
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From: Essex County, NJ
2011 E350 Sport 4Matic - P2 & Drivers Assist / 2010 C300 Sport 4Matic - P2 / 2013 Porsche Cayenne S
There are two reason for this; to introduce understeer in the car to make it safer for ham-fisted drivers and also to compensate for the weight of the engine in the front.
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Junior Member
Joined: Mar 2009
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From: League City, Texas
2008 Mercedes Benz E550 AMG Sport Package
I guess I could buy the safety aspect by lowering the tire pressure up front but isn't there better ways of implementing understeer? Running low tire pressures, as others have stated, is not usually good for mpg or tire wear. Seems more like a last minute engineering fix than a well thought out understeer solution by Mercedes. This also seems curious, if it is indeed the case.
P.S. How many of you have had someone else fill your tires and when you check them (imagine how many drivers don't), they are all at the same 35psi or more, all the way around? Seems like the bone heads at the tire store or the service station would know where to find the correct air pressures for your vehicle by now. This obviously would negate any attempts by Mercedes to control understeer in their vehicles.
Last edited by westcott; Jul 23, 2009 at 09:56 AM.
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From: DC Metro
W210 E55, W211 E3504M, E90 325i
Well factory air pressure recommendation settings are factored in when they are figuring out the desired suspension geometry. All manufacturers lean towards understeer. Even BMWs with their 50/50 distribution have lower front air pressure settings.
I always pump up the front air pressures a couple of notches closer to the rears in all my cars to (hopefully) induce a more neutral stance - not that I push the car hard enough in daily driving to appreciate the difference
I always pump up the front air pressures a couple of notches closer to the rears in all my cars to (hopefully) induce a more neutral stance - not that I push the car hard enough in daily driving to appreciate the difference
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From: McLean, VA
2003 E500 Benz & 2015 BMW M235ix
I use 32 lbs on all four tires, including the brand new Michelins I just installed two weeks ago. I find no significant difference in handling or comfort with increasing the air in the front from the factory recommendation of 28 lbs. And, I've had Goodyear store folks tell me that keeping the air in a vehicle a little higher, even 35 lbs or so, increases the wear life of your tires. You all might recall during the presidental campaign that Obama even said the people could get more gas mileage, thus saving energy costs, if people would inflate their tires to a higher lbs setting. Finally, for those that say Mercedes owners should not worry about saving costs on the operation of their vehicles, whether mileage, repair costs, tire wear, etc, how many millionaires take that attitude............not many or they wouldn't be millionaires.
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From: www.Traben-Trarbach.de
MPG+ ROLFCOPTER
Higher weight due to engine in the front = lower pressure in the front.
You walked in on that one eyes wide open.
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From: Essex County, NJ
2011 E350 Sport 4Matic - P2 & Drivers Assist / 2010 C300 Sport 4Matic - P2 / 2013 Porsche Cayenne S
No seriously hear me out. Because there is extra weight in the front, the engine, you want to decrease the pressure in the tires to give you a more smoother ride. Imagine a beach ball. If you fill it up all the way with air and sit on it and bounce around its going to be uncomfortable for you. If you let some air out and bounce around the shocks will feel more subtle. The same with the car; if you put too much air in the front tires and hit a pot hole it will be more uncomfortable because there is more tendency for the heavy engine to bounce on the hard tires. Take some air out and more energy will be absorbed and less bouncing around. It does make sense...
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From: McLean, VA
2003 E500 Benz & 2015 BMW M235ix
By the way, I used to discount the use of nitrogen in tires instead of air......thought it was just some hype. But when I had my new Michelins installed recently at my MB Dealer, my service rep said that nitrogen keeps a constant pressure in the tires regardless of the outside temperature or heat from the tire running on the pavement.........air pressure in the tires will fluctuate due to temperature changes. So, since they offered the nitrogen, I had them use it and I now see the advantage over just using air to inflate tires.
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Joined: Sep 2007
Posts: 978
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From: Essex County, NJ
2011 E350 Sport 4Matic - P2 & Drivers Assist / 2010 C300 Sport 4Matic - P2 / 2013 Porsche Cayenne S
By the way, I used to discount the use of nitrogen in tires instead of air......thought it was just some hype. But when I had my new Michelins installed recently at my MB Dealer, my service rep said that nitrogen keeps a constant pressure in the tires regardless of the outside temperature or heat from the tire running on the pavement.........air pressure in the tires will fluctuate due to temperature changes. So, since they offered the nitrogen, I had them use it and I now see the advantage over just using air to inflate tires.
Keep us posted on how this is working out for you. I was thinking about trying this out but it makes me a little uncomfortable that I can't just fill my tires with air whenever I need too.
Thread Starter
Junior Member
Joined: Mar 2009
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From: League City, Texas
2008 Mercedes Benz E550 AMG Sport Package
Administrator
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From: www.Traben-Trarbach.de
MPG+ ROLFCOPTER
No seriously hear me out. Because there is extra weight in the front, the engine, you want to decrease the pressure in the tires to give you a more smoother ride. Imagine a beach ball. If you fill it up all the way with air and sit on it and bounce around its going to be uncomfortable for you. If you let some air out and bounce around the shocks will feel more subtle. The same with the car; if you put too much air in the front tires and hit a pot hole it will be more uncomfortable because there is more tendency for the heavy engine to bounce on the hard tires. Take some air out and more energy will be absorbed and less bouncing around. It does make sense...
