41/48 Tire Pressure: The Test Drive ...

Guest (MBNZ) · Jun 4, 2001

Thought I'd start a new thread so this topic wouldn't get lost below ... I want feedback from you guys so I don't go and waste my new rubber. 
 
I changed my tire pressure to 41/48 (front/rear), cold, per the driver's door sill sticker (it specifically lists the make, model and sizes of my '01's Dunlop tires, and states only the 41/48 should be used). 
 
The Test: 3-hours on the Florida Turnpike, 70-90 mph. For about the first two hours, the temp. was 90+ degrees. Then the sky's opened-up and it rained like it was going out of style. 
 
The most pronounced change in feel didn't come from the expeced harsher ride (more about that below), but from the enhanced steering/handling. The Beast was so much more nible at speed, and for a little while, it took a concentrated effort not to oversteer. 
 
The ride was surprising though. More harsh, noticable but not unbearable. The feeling transmitted to me in the driver's seat was more of a 'prounounced bounce' than a thud. Kinda hard to explain it other than over bumps and cracks, the Beast seemed 'bouncier'. 
 
I think the most bothersome attribute that came from increasing the tire pressure had to be the noise. Expansion joints that used to go un-noticed now made their presence known. 
 
An aside: even before the tire pressure change, I am amazed at how well this E55 handles in the rain. Now I'm not talking about average rain, I'm talking about torrents: so bad you can't see the hood emblem. Never a moment of anxiety, sure footed and stable (something I didn't expect with the Beast's wide tires). 
 
Epilog: I love the more nimble steering. I can live with the 'bouncier' ride. But the 'thuds' from road imperfections while running silent (w/o the music playing) are going to drive me crazy (pun intended). 
 
I'd love some feedback from you guys on this one. 
 
Drew.

Guest (MBNZ) · Jun 4, 2001

I've always had my tire pressure at 41/48

Drew, I will do a test and reduce my tire pressure to 36/38 and let you know how it feels (hope i don't drive the tires off the rims..) Since I've always had it at 41-front & 48-rear, I've only known the great handling that you've experienced. I didn't experience any excessive tire noise or rut steering that you've noticed although mine came with a different setup... I have Michelin Pilot Sport tires...same size as yours. They are great tires..no complaints. Will let you know how it feels... Regards, Edmond

Guest (MBNZ) · Jun 5, 2001

33 psi?? Might as well be 4 jelly donuts!

I got my car from the dealership with around 34 psi. I felt the care handled very well for a sedan. After driving for a couple weeks I just happened to be at a filling station. I remember my pappy always telling me to look at the doorjamb for the 'official' tire psi, so I did. I ended up putting 40psi all around and the difference in ride was immediately noticeable. Going from a Corvette the the E55 I had lost some of the 'crispness' of sharp cornering. I got that back once I inflated the tires. Yes the roads in Detroit area are HORRIBLE and no I don't do much highway driving (unfortunately) so I lose most of the benefits of having the higher air pressure. I don't care. If I can take a street corner at 25 that's almost as fun as an 'S' curve. I bought this car for performance. the fact that it has a back seat and lots of room are a definite plus, but I want every penny of the 78k I paid in performance please! therefore I'll keep the tires firm and the ride louder and harder. Maybe when I'm old (say 35) I'll take the pressure down a few notches to soothe my old bones. : ) (and 33 if you have to ask)

Guest (MBNZ) · Jun 5, 2001

UK tyres

Tyres in the UK are Bridgestones. From experience, the best tyres (as well as the most expensive) are Michelins, even if they are French

The pressure chart inside the fuel flap on my E55 lists:<UL> Up to 130mph 31 Front, 33 Rear (Light load) 32 Front, 34 Rear (Full load) Over 130mph 36 Front, 36 Rear (Light load) -- what I use 41 Front, 48 Rear (Full load) </UL> Just for your info, really... not sure if it helps at all

I have to say that coming down from 41 / 48 has improved the ride quality and noise levels immensely. I was also shocked to find that, after buying the car, the nearside tyre was at 30 whereas the offside tyre was at 40. The effect of this was that the steering was 'left hand down' giving the impression the tracking was out. Balance the pressures and it was OK. Just goes to show just how much of an effect pressures can have on this kind of car... Jamie -- London, UK.

Guest (MBNZ) · Jun 5, 2001

Jamie: What does the sticker on your driver's side door say?

Guest (MBNZ) · Jun 5, 2001

Aaron: Should the tire pressure be the same in both the front and rears?

Guest (MBNZ) · Jun 5, 2001

It says...

Daimler-Benz AG Typ: 210 PZ: 3 Ehrlich

The pressure chart on Euro E55s is, somewhat bizarrely, inside the fuel cap... Jamie -- London, UK.

Guest (MBNZ) · Jun 5, 2001

What's the pressure recommendation inside the door?

Guest (MBNZ) · Jun 5, 2001

A reasonable compromise...

Unless you're tracking the car or frequently blasting past 130mph, I would think 36/40 would be a decent trade-off between crisp handling/steering and comfort/noise. The 'bouncier' feeling, I suspect, is the 48psi in the rear. With 33psi, the tire was able to cushion some of the road imperfections. With 48, the burden is more on the suspension (and your butt). When I had my 996, the Porsche board discussed this at length as well. There were many, including those who tracked the car, who believed running 32/36 was preferable to the recommended 36/42. In any event, I've been running 36/40 which has lessened the rear end bounce. I'm thinking about toying around with 36/38 to experiment. By the way, I'd guess the 41/48 factory recommendation was pushed harder by MB counsel than the AMG track experts.

Guest (MBNZ) · Jun 5, 2001

US E55 have what I think is our 'normal' E-Series tire pressure ratings on the Fuel-Filler Door ...

... as well. But they also have an additional sticker placed on the door-jam of the driver's side door which specifically denotes the make and size of tires on the E55, as well as the pressure ratings (again, mine says 41/48).

Guest (MBNZ) · Jun 5, 2001

You will kill the tires in 8-9 months at higher tire pressures 41/48 cold probably means 45/53 hot and therefore the car will be sitting on the center of the tire instead of being spread across the entire width of the tire. 34/34 or 36/36 is a good compromise I think and will give you well over a year's worth of driving. However long hauls with higher speeds and aggressive driving I do recommend higher pressures for that nimblier feel. The newer Pilot Sports which are on my E do have a little harder compound than before so that may extend the tire life, although the design change was for bettter handling in the wet.

Guest (MBNZ) · Jun 5, 2001

Nope, no sticker on the door pillar... honest

Guest (MBNZ) · Jun 5, 2001

Re: A reasonable compromise...

I agree with you Bob. I think I'll do some more experimenting and see what feels right. My only concern in deciding on the right pressure is accelerated tire wear.

Guest (MBNZ) · Jun 5, 2001

Re: Re: 41/48 Tire Pressure: The Test Drive ...

I hear ha Mike. I'm not going to stay at 41/48. I will start experimenting and see what feels best. As I said above in response to Bob, I am most concerned about the accelerated tire wear. BTW: being the only other E55 I know of in S. Florida, we should get together for a cold one some day. Drew.

Guest (MBNZ) · Jun 5, 2001

I believe you!

 Jamie, I've gone back through old threads looking for info. on your car, but couldn't find much. What year? Color combo? Options? With the 'tyre talk', I guess you've got me curious about other differences between US and Euro E55's. If you know of any, please do tell, and if you have pictures, that would be great too! Cheers, Drew.

Guest (MBNZ) · Jun 5, 2001

Question for Drew........or anybody with an E55- Tire Pressure

Drew, correct me if I am wrong but the inside of the gas filler door shows 41/48 PSI as a recommendation with 5 passengers and a full trunk (there are pictures of the people and boxes)??? I was running 41/48 for the last 5k miles and there is a slight wear pattern in the centers of my rear tires. This could be attributed to overinflation. I have since reduced my pressure levels to 38/38.

Guest (MBNZ) · Jun 5, 2001

Re: Question for Drew........or anybody with an E55- Tire Pressure

Vic, On my fuel filler door is the following: Speeds up to 130 MPH: - 3 people/ 1 bag = 29/30 - 5 people/ 3 bag = 32/39 Speeds over 130 MPH: - 3 people/ 1 bag = 33/35 - 5 people/ 3 bag = 38/48 I'm thinking that the fuel door sticker is standard on the E-Class, and the sticker inside the driver's door is added at the AMG factory.

Guest (MBNZ) · Jun 6, 2001

Re: Re: Question for Drew........or anybody with an E55- Tire Pressure

On my 2001 fuel cover it's the same as Vic55; I think that you are right about the information being the same as the E430, but I guess they've just started putting these instructions in recently. The 41/48 is for five passengers and luggage.

Guest (MBNZ) · Jun 6, 2001

Re: Aaron: Should the tire pressure be the same in both the front and rears?

I'm not sure exactly why I did 40 all around. Seemed like a good idea at the time. : ) Is it better to have more pressure in the rear? They are bigger tires I suppose. I fiddle around with 36 or 38 in the front and stick with 40 in the rear.

Guest (MBNZ) · Jun 7, 2001

Pictures on the way...

Some really beautiful weather here at the moment, and some excellent backdrops (okay, not quite up to the likes of NYC skyline or Monument valley) so I may get clicking with the digital. The car is a '99 in Azurite Blue with Silver/Black interior. It has every conceivable extra bolted down inside, from Xenons back to an electric rear blind but sadly excluding lumbar

I'm not sure of the differences between Euro and U.S. cars; for sure UK cars have the steering wheel on the 'right' side

I would imagine that cars destined for the North American markets would come better spec'd as standard. Jamie -- London, UK.

41/48 Tire Pressure: The Test Drive ...

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