Mercedes recommends a normal load pressure of 29 psi for the 275/55R17 tires. This is the low end of the operating range and is targeted towards those who are most interested in a smoother ride. Higher tire pressures are used for increased loading, more nimble handling, reduced tire edge wear and lower rolling resistance. I run mine at 30 psi, as measured in my garage prior to driving.
It is very common for even the service techs at the Mercedes dealer to overinflate the tires. I complained to the service manager on my last visit because my ML430 was returned to me with the tires overinflated (second time!).
motoadve - 2/22/2005 5:39 AM
I changed from a 16 to a 17 inch wheels, now the ride feels stiffer, what air pressure you guys recommend on 17" tires?
It depends how different your wheels (weight) and tires (design, material, etc) are from the OEM specs and recomendations.
If you have a different brand of tires which have a different material, shape, design, reinforcement than than the OEM suggested ones, then the feedback to your shocks may be different.
If your wheels are heavier, then there is more up-sprung weight that your shocks have to dump and the ride will be harsher.
Mercedes, as well as all companies, perform tuning on their shocks using only their recomended wheels/tires since they cannot test all tire brands, materials, designs, etc.
What this means is that you need to experiment with the tire pressure having the pressures listed on your gas cap as a good starting reference.
Higuer pressure means more feedback to the shocks and therefore the valving/disks on the shocks will increase the dumping effect/settings and the vehicle will have a more controled ride at higher speeds, but too much feedback to the shocks will create a harsh ride at high speeds. But, it may provide a nice non-wobbly ride at lower speeds.
Lower pressure on your tires will provide a smoother ride at higuer speeds, but it may be too wobbly at lower speeds.
When your shocks are getting worn out, you may not be able to find a good setting, since you will need to add more pressure to your tires to compensate the worn shocks but your tires will not absorb the road/terrain vibrations/feedback and the ride will not feel smooth and quiet, and the optimal settings for a confortable ride at high speeds may not work for lower speeds and viceversa.
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