axchung

I was filling my tires yesterday with nitrogen when i realized the pressure recommendation for the 550 is 35 fronts and 42 rear. I was running 35 all around and now i feel the ride much harsher(obviously). Is everyone running at the recommended pressure? I'm tempted to bring it back down to 35 in the rear but 7psi seems to be a big difference.

StevethePilot

On my 320, which is running 265/60 R18 Michelins front and back, it says 32psi for normal operations front and back, 38psi in the rear for carrying heavy loads. My old 1986 Mercedes recommended something like 6 or 7 pounds more in the rear for extended operations over 100mph (probably for cooling more than anything), but as you can see 6psi more for the rear is recommended even on the 18 inch rims.

STP

PS What other differences are you noticing with the nitrogen?

emayer

I run the GL 550 at 36 front and 40 rear which is a nice compromise.

BTW there is no real advantage to using nitrogen other than the fact that it may diffuse more slowly thereby maintaining pressures longer. From a safety (and cost) perspective I would simply recommend checking more frequently and using air to adjust. Especially important as the ambient temps in the NE are fluctuating considerably this time of year...

axchung

STP

PS What other differences are you noticing with the nitrogen?[/QUOTE]

I had nitrogen on my Range Rover on 22's rims and did notice that they retained the pressure longer than usual. They claim that nitrogen improves fuel efficiency(which i never kept track of), improves safety(proper inflated tires will give you that), reduces tire oxidation(i didn't know tires oxidized;i guess less water than regular air) and lower running temperatures(that i believe and i guess that improves performance).
The shop that i originally got it filled gave a 1 year warranty and to my surprise they filled my GL under the same warranty and a nice tip.

nantucketsleigh

[QUOTE=StevethePilot;2765741]On my 320, which is running 265/60 R18 Michelins front and back, it says 32psi for normal operations front and back, 38psi in the rear for carrying heavy loads. My old 1986 Mercedes recommended something like 6 or 7 pounds more in the rear for extended operations over 100mph (probably for cooling more than anything), but as you can see 6psi more for the rear is recommended even on the 18 inch rims.

Higher rear vs front tire pressure usually promotes understeer and inhibits oversteer. I prefer the handling characteristics of equal pressure all around.

emayer

I think the benefits you list (other than maintaining pressure- by reduced diffusion- and oxidation?) are functions of consistent and appropriate tire pressures not the gas itself. While I couldn't justify the expense of using nitrogen as opposed to checking pressures regularly and filling with air, if you can get the nitrogen for free go for it!

Comfy_Couch

Here's an article in the WSJ discussing the benefits of nitrogen.

emayer

An article and analysis from Consumer Reports demonstrating no significant advantage to using nitrogen:

http://blogs.consumerreports.org/car...nitrogen-.html