[musides]

I'm starting to experiment a bit with tire inflation. I have stock tires (195/70 R14), which the book states should be 28 psi in the front and 32 psi in the back. I find this a bit odd considering most of the vehicle weight is in the front, so my current configuration is 32 psi in the front and 34 in the rear.

This has been quite comfortable driving and handles turns quite well. I had been at 30 psi in the front and 32 in the rear, and I find the new higher pressure I'm using drives better.

I'm wondering what other folks have tried and experimented with?

 

[Rmac58]

I inflate the fronts 2 to 4 psi lower than the rears, which are at the maximum cold pressure for the tire set by the TIRE manufacturer.
Technology marches on. These cars have very good suspensions. I inflate the tires for mileage purposes.

 

[mbkomfort]

Yes, 32 front, 36 rear, Wagon with 205/65-15 cold tires..

 

[Zedd]

34 front 36 rear.

 

[benzmizer]

Front 30; Rear 32 (185/70R14)

 

[musides]

I inflate the fronts 2 to 4 psi lower than the rears, which are at the maximum cold pressure for the tire set by the TIRE manufacturer.
Technology marches on. These cars have very good suspensions. I inflate the tires for mileage purposes.

Right, mileage is the goal. Apparently though, over inflation can become a safety issue due to degraded handling. I'm particularly interested in what you say about maximum cold pressure. My tires are rated for a max of 44 psi. This seems to be tempting fate though -- roadways get quite hot in the summer, and the tires can get even hotter.

In any event, anyone know the logic behind front tires being less than the rear? I've done some searches, but no one has really produced a definitive answer. The main speculation is that it improves handling since it is a front wheel drive vehicle. Just a curiosity. Anyone have any data on how much increased inflation improves your mpg?

 

[hheynow]

32 front
34 rear

 

[MBZ300CD]

30 Front
32 Rear
Filled with Nitrogen
Rotated every 7,500 +/-
They have given me over 100,000 miles with no issues.

 

[Rmac58]

Right, mileage is the goal. Apparently though, over inflation can become a safety issue due to degraded handling. I'm particularly interested in what you say about maximum cold pressure. My tires are rated for a max of 44 psi. This seems to be tempting fate though -- roadways get quite hot in the summer, and the tires can get even hotter.

In any event, anyone know the logic behind front tires being less than the rear? I've done some searches, but no one has really produced a definitive answer. The main speculation is that it improves handling since it is a front wheel drive vehicle. Just a curiosity. Anyone have any data on how much increased inflation improves your mpg?

I haven't had any handling issues either, but I don't race the car. Again, we're dealing with a well engineered suspension.

You'd have to do a test for mpg, I have not.

If you're familiar with Click & Clack of public radio fame(?), they put the question to a tire pro, the tire will increase in pressure as it heats up, but by 4 to 5 psi max. The pressure on the side of the tire has this built in.

IIRC, the differences in front & rear pressure are mainly for a loaded trunk, see pic, that is of my SD. If you drive really fast, add psi.

 

[musides]

30 Front
32 Rear
Filled with Nitrogen

Interesting. Just did some looking up on nitrogen. Apparently Consumer Reports did a review in January 2008 (according to the NY Times) that showed nitrogen lost 1.3 psi less per year than air. That equates to around a 30% improvement, which is surprising considering that air is already 78% nitrogen. I suppose if it were free it may be worth it.

 

[musides]

You'd have to do a test for mpg, I have not.

Will do. Hmm, I suppose I'll switch to a weekly fill up and try different pressures. That may produce some reasonable results within a month or so.

Interesting on Car Talk taking this on. I think I'd still hesitate to go over 40 psi though.

I don't think trunk load should matter, since the weight of the engine ought to trump anything in the trunk considerably.

 

[MBeige]

Just a reminder, for those with climates that are beginning to get cold, to check your tire pressures (here in southern CA the temps just dropped).

I'm trying on 36PSI front and rear. Used to be 33 all around. Running on 205/60/15 (shouldn't matter what tire size it has, unless it's a larger volume tire than factory recommended size).

 

[Nutz 4 Benz]

40 psi, front and rear.

 

[ronw123w124]

32psi all around.

 

[slcturbo]

Not to be a dweeb, but what is wrong with sticking with the tire pressures recommended by Mercedes? Is the group think that tire composition has changed over time and we should now run different tire pressures? It seems like the Mercedes recommended tire pressures are kind of low.

 

[PlaneCrazy]

250 kPa at the rear, 230 kPa at the front, as per Mercedes' recommendation "for continued high speed travel".

What the hell is a PSI?

 

[Nutz 4 Benz]

What the hell is a PSI?

Aren't you an engineer

 

[PlaneCrazy]

Yes, I am, which is why I don't rely on such ancient and ambiguous units that lead to such mistakes...

 

[slcturbo]

250 kPa at the rear, 230 kPa at the front, as per Mercedes' recommendation "for continued high speed travel".

What the hell is a PSI?

Pounds per Square Inch. What is a kPa?

 

[MBeige]

Not to be a dweeb, but what is wrong with sticking with the tire pressures recommended by Mercedes? Is the group think that tire composition has changed over time and we should now run different tire pressures? It seems like the Mercedes recommended tire pressures are kind of low.

The factory numbers are set for maximum comfort.