[ER Doc]

Hi everyone,

I'm relatively new to the MB world and have been trying to find a way to upgrade the handling characteristics of my relatively new 2006 C350 4Matic. compared to my wife's BMW X3 (an SUV), the BMW ride was soft and vague. I guess I shouldn't be surprised given the 4Matic only comes in "Luxury" trim, but I expected better from MB. I initially considered getting stiffer swaybars but after some research, came to the conclusion that noone makes stiffer swaybars for the 4Matic line. I also considered getting bigger rims with stiffer tires, but the fact that I live in the snowbelt of Ohio makes that impractical (unless I want to get a set of snow tires as well, but then we're getting pricey). So finally I did some research and discovered that just by putting a little extra air in my tires, I could achieve surprisingly dramatic changes in handling and road-feel.

After reading this thread, I went an increased the tire pressure in all 4 tires up to 40 psi (from 30/32 in the front/rears, respectively). What a difference! The car no longer feels vague and mushy, and corners much more crisply. On the downside, pot holes and railroad tracks that I had previously ignored are much more noticiable now. I think I may drop the pressures down to 36/38, but I doubt I'll go much lower than that.

Has anyone else experimented with this? If so, I'd be curious to hear their opinions.

 

[NJBNZ]

I don't really think you can consider putting air in your tires a "performance upgrade"

 

[Tom4697]

I don't really think you can consider putting air in your tires a "performance upgrade"

I was just about to say the same,
Also, doesn't over inflating your tires cause more damage then benefits, like more prone to rupture with the extra pressure and also premature tire wear ? Just wondering.
T.

 

[Buellwinkle]

People that autocross measure temps different parts of the tread pattern to adjust air pressure and this typically runs 50 psi but that's because they never go straight. So yes, extra pressure will increase your tires ability to grip laterally at a compromise lonitudanal grip. So you accomplished one thing and ruined 4 others, ride comfort, tread life, braking and accelleration (although you can burn rubber more easily,haha).

What would be better is to get tires with the sidewall flexability that meets your needs. Not all Z rated tires are made the same. If latteral performance is key, then consider tires with stiffer sidewalls, comfort is key, consider softer sidewalls.

 

[ER Doc]

I can't say I've noticed any change in braking or acceleration (certainly no tirespin, which would be pretty downright amazing given that fact that my car is a 5 speed automatic with 4Matic AWD and ESP stability control). With regards to treadlife, since you're recommending I buy different tires anyhow, I can't say I'm terribly concerned.

 

[Buellwinkle]

Sure, I agree that these cars have safety electronics that prevents you from noticing loss of braking and accelleration due to less grip but electronics can't change the laws of physics, just mask them.

 

[FrankW]

if you really want to improve the handling you can now opt for the PSS9 coilover from Bilstein. They now make the coilover for the 4-matic. part # F4-GM5-8860-H0

came across it when I got bored and searched around. hope this helps the 4-matic guys.

 

[ATL_MB]

I typically keep 40 psi in my tires (front and rear) -- it does make a difference to me, especially in initial turn-in. Potholes, etc, feel a bit harder and sound louder, but I have never had any wheel or tire damage (and running low profile tires).

And I am not sure that having a set of summer and a set of winter tires/wheels will cost that much more in the long run. Both sets of tires will last longer so it is really only the wheels which you are paying extra for. And for that you get far better traction, performance and safety in both winter and summer.

And obviously, new PPS 9 coil overs will make a huge difference!

 

[ER Doc]

I think I'll hold off on the $1700+ bilstein kit for now (especially since I don't know what effect they would have on the warrenty) but when my current tires wear out (apparently prematurely) I may consider getting a set of summer tires on wider rims and put snow tires on the OEMs. In the meantime, running the tires with 20% higher pressures really does seem to offer noticable performance improvements, particulary with regards to reducing oversteer, without any significant downside (other than the harder ride, but my wife's BMW has always felt like that with it's standard tire pressures). Interestingly enought, the June issue of Car and Driver alludes to this "performance" modification in their "Demon Tweaks" article on page 148 when they were trying to get better handling out of a Subaru Forester 2.5XT (they ended up having to use aftermarket swaybars to get the performace they wanted however).

If someone comes across any swaybars for the 4Matic, BTW, please PM me! Those I could probably sneek a couple of those past the wife's death grip on the bank account...

 

[RodrigoMex]

Tweaking with tire pressures has been one of the multiple "adjustments" made for street and track since the invention of tires. Theres nothing new to discover in this theory field, and every aspect of tire life expectancy, traction ,and handling area can be easily found on the web.

For me that live in a city with half the potholes in the world, 40psi all around on a 2005 C230 KSS has been wonderful. Tires are more protected this way. What makes bubbles in the tire after hitting a pothole is not the excessive pressure, but the opposite, as a knife effect is present when the rubber "bends" so much thar the rim cuts the sidewall .

"Overinflating" really is only when you inflate your tires at more pressure than the one they are designed for. (check your tire max psi specs on the sidewall and never get close to it, specially if not using "pure" Nitrogen instead of air). OEM specs are designed for a mixture of comfort and handling, but you never get the best of both worlds. That doesn't mean you should accept comments referring to 40 psi all around as a "fool thing" to do. I don't know the US tire specs of MB models, but I'm comparting to my 225/45/17 - 245/40/17 tires.

If you want better handling 38-40 psi all around is a nice choice (and your tires will be MORE protected to potholes). For more oversteer increase the pressure in the rears and lower in the fronts, for more understeer just do the opposite. At this tire pressures is with which I normally play not only in the city, but also at track days.

Good luck.:thumbsup:

 

[C230mb]

hey er doc,

being in the neighborhood and visiting Cleveland on a frequent basis, i know the roads and potholes can be pretty ugly. i had an 06 C230 sport which has a pretty stiff suspension and low profile tires--handled great, but if you needed it for comfort, it was pretty brutal. i visit CCF on a pretty regular basis, and riding up the MLK to the hospital is enough to knock the water out of you.

i'd drive around for a while and make sure you really want to change, especially if it's a daily driver. i wish i would have gotten a C 4matic instead of a rwd sport at the time of purchase. i traded for a 525xi which is buick like compared to the c230, but it doesn't beat the heck out of your kidneys.

cheers!

 

[ER Doc]

Tweaking with tire pressures has been one of the multiple "adjustments" made for street and track since the invention of tires. Theres nothing new to discover in this theory field, and every aspect of tire life expectancy, traction ,and handling area can be easily found on the web.

For me that live in a city with half the potholes in the world, 40psi all around on a 2005 C230 KSS has been wonderful. Tires are more protected this way. What makes bubbles in the tire after hitting a pothole is not the excessive pressure, but the opposite, as a knife effect is present when the rubber "bends" so much thar the rim cuts the sidewall .

"Overinflating" really is only when you inflate your tires at more pressure than the one they are designed for. (check your tire max psi specs on the sidewall and never get close to it, specially if not using "pure" Nitrogen instead of air). OEM specs are designed for a mixture of comfort and handling, but you never get the best of both worlds. That doesn't mean you should accept comments referring to 40 psi all around as a "fool thing" to do. I don't know the US tire specs of MB models, but I'm comparting to my 225/45/17 - 245/40/17 tires.

If you want better handling 38-40 psi all around is a nice choice (and your tires will be MORE protected to potholes). For more oversteer increase the pressure in the rears and lower in the fronts, for more understeer just do the opposite. At this tire pressures is with which I normally play not only in the city, but also at track days.

Good luck.:thumbsup:

Thanks for the input and thanks for telling me that I'm not crazy for trying this (which is certainly a lot cheaper that buying new suspension components/tires/wheels/etc.).

I'll try dropping the pressures just in the front tires then and see if I notice a difference. The max psi on the sidewalls of my Continentals are 44 psi, so I should be okay. I see your point; I guess I'm not technically "overinflating" the tires if I'm keeping them within tire manufacturer's recommended pressure range.

 

[BARW126420SEL]

The 40 pounds of air is fine. I would recommend a nice stiff set of shocks. That way you can keep your ground clearance for the snow. I don't know if bars from a C-Class AMG would work, but that my be a good alternative. Maybe you can get C55 bars and shocks. I just don't know if those shocks will work with your longer springs.

 

[brabus]

not that its overly important to most people, but increasing the tyre pressures also give you less drag and therfor give you better fuel economy.


ive always run my cars around 33psi, but now that i think about it, might aswell have the handling edge and crank it up closer to 40psi.

 

[InTTruder]

Tweaking with tire pressures has been one of the multiple "adjustments" made for street and track since the invention of tires. Theres nothing new to discover in this theory field, and every aspect of tire life expectancy, traction ,and handling area can be easily found on the web.

For me that live in a city with half the potholes in the world, 40psi all around on a 2005 C230 KSS has been wonderful. Tires are more protected this way. What makes bubbles in the tire after hitting a pothole is not the excessive pressure, but the opposite, as a knife effect is present when the rubber "bends" so much thar the rim cuts the sidewall .

"Overinflating" really is only when you inflate your tires at more pressure than the one they are designed for. (check your tire max psi specs on the sidewall and never get close to it, specially if not using "pure" Nitrogen instead of air). OEM specs are designed for a mixture of comfort and handling, but you never get the best of both worlds. That doesn't mean you should accept comments referring to 40 psi all around as a "fool thing" to do. I don't know the US tire specs of MB models, but I'm comparting to my 225/45/17 - 245/40/17 tires.

If you want better handling 38-40 psi all around is a nice choice (and your tires will be MORE protected to potholes). For more oversteer increase the pressure in the rears and lower in the fronts, for more understeer just do the opposite. At this tire pressures is with which I normally play not only in the city, but also at track days.

Good luck.:thumbsup:

A good commentary.

I typically 'adjust' tire pressures depending on whether I'm hauling the granddaughter or hauling @$$. Every tire/suspension is a compromise, so you can use adjustability (pressure) to get something. There is no such thing as a free lunch, as RM mentioned. You may see more wear, and some decrease in comfort. So be it.

 

[RodrigoMex]

The 40 pounds of air is fine. I would recommend a nice stiff set of shocks. That way you can keep your ground clearance for the snow. I don't know if bars from a C-Class AMG would work, but that my be a good alternative. Maybe you can get C55 bars and shocks. I just don't know if those shocks will work with your longer springs.

In this field I had never had the best of both worlds either (comfort Vs handling), until I accepted to use Koni FSD's in the benzie. Believe me, better comfort at the streets and better handling at the track with this "new" shocks. I highly recommend them.

OE MB Sport springs are "nice", just the same spring height and almost same stiffness as the Eibach Prokit.

With this combo I personally feel a very neutral handling in my car at the track (4 cil Kompressor). C32 and C55's have larger back sway bars (or at least they should), because that extra weight at the front generates a lot more understeer. If the C230 KSS is quite neutral, going to stiffer rear sway bar will generate a "tail happy" ride, which is not precisely the most wanted for a street car.:thumbsup: