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GL450 Suspension
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Posted 10/1/2007 3:35 PM
ravicchio

Date registered: Dec 1899
Location:
Vehicle(s):
GL450 Suspension

I just purchased a (used) 2007 GL 450 and love it except it has a sloppy and loose drive. I know it's a SUV but it still feels very loose
for the reviews it received. My car has 18" tires....not sure if 19" would make much of a difference. People say they love the way this
car drives but I do not. Are there any aftermarket sway bars or suspension mods for the GL450? Does anyone else feel the same about
the suspension, or am I alone on this.
Thanks
#90647
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Author
Posted 10/1/2007 6:39 PM
cmitch
Expert




Date registered: Apr 2006
Location: Ala-Tenn
Vehicle(s): 2002 ML320, 2005 S430 4Matic, 2010 F150 Super Crew
Posts: 3412
2000
RE: GL450 Suspension

I'd check for low air pressure in the tires. While opinions differ on this, it's better to run at or a little above maximum air pressure for best performance.
#90659 - in reply to #90647
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Posted 10/1/2007 7:30 PM
AsianML

Date registered: Dec 1899
Location:
Vehicle(s):
Re: GL450 Suspension

What suspension setting do you have it in?
#90664 - in reply to #90659
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Author
Posted 10/1/2007 8:08 PM
Marsden
Classic MB




Date registered: Apr 2006
Location: Capital City USA
Vehicle(s): Mercedes-Benz
5000
RE: GL450 Suspension

I'd check for low air pressure in the tires. While opinions differ on this, it's better to run at or a little above maximum air pressure for best performance.

He means at or a little above rated air pressure (info supplied by MB in your owner's manual, door jambs and/or fuel filler cap

 

#90670 - in reply to #90659
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Author
Posted 10/1/2007 11:45 PM
cmitch
Expert




Date registered: Apr 2006
Location: Ala-Tenn
Vehicle(s): 2002 ML320, 2005 S430 4Matic, 2010 F150 Super Crew
Posts: 3412
2000
RE: GL450 Suspension

Marsden - 10/1/2007 7:08 PM

I'd check for low air pressure in the tires. While opinions differ on this, it's better to run at or a little above maximum air pressure for best performance.

He means at or a little above rated air pressure (info supplied by MB in your owner's manual, door jambs and/or fuel filler cap)

 

Thanks!! My tire dealer always inflates my Michelins about 5 over the maximum rated pressure located on the MB tag ( I just checked them with my tire pressure gauge and the MB recommendation is 36 on back and 32 on front, I run 40 to 42 on back and 36 to 38 on front). The Pirellis and the Michelins are rated both at 44PSI maximum pressure. I've found inflating the tires to more pressure improves performance and tire wear but it stiffens the ride a bit.

#90678 - in reply to #90670
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Author
Posted 10/2/2007 2:17 AM
Marsden
Classic MB




Date registered: Apr 2006
Location: Capital City USA
Vehicle(s): Mercedes-Benz
5000
RE: GL450 Suspension

Not to belabor the point unnecessarily, but I think you're near the danger zone. Because actual pressures when hot (after highway driving for instance) are roughly 3psi higher than cold. So your 42+3=45 => excess of rated max.

What really surprises me is that your tire max pressure is only 44 psi. I guess because they're truck tires. For example, my new Pirellis say 51 psi max on the sidewall, but they are car tires and Z-rated besides (makes sense that Z-rated tires would have a higher bursting pressure). Mercedes calls for 29/32psi (f/r) on my car (CL500) and that's what I follow, FWIW. Actually a little bit higher on front

Now, having said all of that, I do agree with your original point that underinflation, in addition to being vastly more common than overinflation, can contribute to the symptoms the OP was relating.

 

#90707 - in reply to #90647
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Posted 10/2/2007 9:36 AM
cmitch
Expert




Date registered: Apr 2006
Location: Ala-Tenn
Vehicle(s): 2002 ML320, 2005 S430 4Matic, 2010 F150 Super Crew
Posts: 3412
2000
RE: GL450 Suspension

Marsden - 10/2/2007 1:17 AM

Not to belabor the point unnecessarily, but I think you're near the danger zone. Because actual pressures when hot (after highway driving for instance) are roughly 3psi higher than cold. So your 42+3=45 => excess of rated max.

What really surprises me is that your tire max pressure is only 44 psi. I guess because they're truck tires. For example, my new Pirellis say 51 psi max on the sidewall, but they are car tires and Z-rated besides (makes sense that Z-rated tires would have a higher bursting pressure). Mercedes calls for 29/32psi (f/r) on my car (CL500) and that's what I follow, FWIW. Actually a little bit higher on front

Now, having said all of that, I do agree with your original point that underinflation, in addition to being vastly more common than overinflation, can contribute to the symptoms the OP was relating.

 

Wide tires are rated substantially lower than narrower ones. What are your tire's width? Are they regular width sedan tires or wider sport tires? As I pointed out, no tire manufacturer is going to put the actual maximum PSI on the sidewall because of liability issues. If they put 55 to 60 PSI on a tire rated for 44, what would happen if they manufactured a defective tire? They're going to lleave themselves some margin of error.

#90728 - in reply to #90707
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Posted 10/2/2007 4:32 PM
AsianML

Date registered: Dec 1899
Location:
Vehicle(s):
Re: GL450 Suspension

Isn't it also the "thinner" the tire the higher the PSI?
#90768 - in reply to #90647
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Author
Posted 10/2/2007 5:56 PM
cmitch
Expert




Date registered: Apr 2006
Location: Ala-Tenn
Vehicle(s): 2002 ML320, 2005 S430 4Matic, 2010 F150 Super Crew
Posts: 3412
2000
Re: GL450 Suspension

AsianML - 10/2/2007 3:32 PM Isn't it also the "thinner" the tire the higher the PSI?

You're making my head hurt! 

#90778 - in reply to #90768
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Posted 10/2/2007 11:40 PM
Marsden
Classic MB




Date registered: Apr 2006
Location: Capital City USA
Vehicle(s): Mercedes-Benz
5000
RE: GL450 Suspension

cmitch - 10/2/2007 9:36 AM
Marsden - 10/2/2007 1:17 AM

Not to belabor the point unnecessarily, but I think you're near the danger zone. Because actual pressures when hot (after highway driving for instance) are roughly 3psi higher than cold. So your 42+3=45 => excess of rated max.

What really surprises me is that your tire max pressure is only 44 psi. I guess because they're truck tires. For example, my new Pirellis say 51 psi max on the sidewall, but they are car tires and Z-rated besides (makes sense that Z-rated tires would have a higher bursting pressure). Mercedes calls for 29/32psi (f/r) on my car (CL500) and that's what I follow, FWIW. Actually a little bit higher on front

Now, having said all of that, I do agree with your original point that underinflation, in addition to being vastly more common than overinflation, can contribute to the symptoms the OP was relating.

 

Wide tires are rated substantially lower than narrower ones. What are your tire's width? Are they regular width sedan tires or wider sport tires? As I pointed out, no tire manufacturer is going to put the actual maximum PSI on the sidewall because of liability issues. If they put 55 to 60 PSI on a tire rated for 44, what would happen if they manufactured a defective tire? They're going to lleave themselves some margin of error.

Yeah I see what you're saying; I just wouldn't want to play with fire. 

Anyway, my tires on the CL are 235/55ZR17.  

Do you inflate less in the snow season? 

 

 

 

#90811 - in reply to #90728
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Author
Posted 10/3/2007 7:05 AM
AsianML

Date registered: Dec 1899
Location:
Vehicle(s):
RE: GL450 Suspension

Marsden - 10/2/2007 11:40 PM
cmitch - 10/2/2007 9:36 AM
Marsden - 10/2/2007 1:17 AM

Not to belabor the point unnecessarily, but I think you're near the danger zone. Because actual pressures when hot (after highway driving for instance) are roughly 3psi higher than cold. So your 42+3=45 => excess of rated max.

What really surprises me is that your tire max pressure is only 44 psi. I guess because they're truck tires. For example, my new Pirellis say 51 psi max on the sidewall, but they are car tires and Z-rated besides (makes sense that Z-rated tires would have a higher bursting pressure). Mercedes calls for 29/32psi (f/r) on my car (CL500) and that's what I follow, FWIW. Actually a little bit higher on front

Now, having said all of that, I do agree with your original point that underinflation, in addition to being vastly more common than overinflation, can contribute to the symptoms the OP was relating.

 

Wide tires are rated substantially lower than narrower ones. What are your tire's width? Are they regular width sedan tires or wider sport tires? As I pointed out, no tire manufacturer is going to put the actual maximum PSI on the sidewall because of liability issues. If they put 55 to 60 PSI on a tire rated for 44, what would happen if they manufactured a defective tire? They're going to lleave themselves some margin of error.

Yeah I see what you're saying; I just wouldn't want to play with fire.

Anyway, my tires on the CL are 235/55ZR17.

Do you inflate less in the snow season?

 

 

 

For each 10 degree drop in temperature, the tires will lose about 1 (I heard 2 on from some other sites) PSI. So the ML at the 39-40 PSI we keep it at in the summer will drop to about 30-32 PSI in the winter. If you've ever looked at a very underinflated tire, it;s also wider because a small portion of the sidewall pretty much becomes part of the contact patch now, and you don't want wider in the snow.


Edited by AsianML 10/3/2007 7:06 AM
#90839 - in reply to #90811
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