Just wondering how obsessive I should be about keeping the pressure at the recommended 30/33 pounds. At what point--plus or minus-- does it begin to make a real difference in tire wear or performance. With other cars I usually haven't paid much attention unless it gets to be plus or minus 5 pounds. Believe it or not I found a station in this little town that still has a free air pump.
Tire Pressure
1 - 6 of 6 Posts
You can search and find alot of info on this topic, but I can summarize.
The factory recommended pressures are meant to be a balance of comfort, grip, and treadwear. Higher pressure will increase grip and treadwear and decrease comfort. You really need to experiment yourself because comfort, grip, and treadwear are also very dependent on the exact brand/model tire you have.
A few of us have found that around 35-36psi on all four tires is a good setting for everyday driving that yields minimal reduced comfort and better grip and treadwear.
To answer your question specificially, the factory pressures should be considered minimum. Dropping 5psi below those pressures will affect treadlife and grip dramatically.
The factory recommended pressures are meant to be a balance of comfort, grip, and treadwear. Higher pressure will increase grip and treadwear and decrease comfort. You really need to experiment yourself because comfort, grip, and treadwear are also very dependent on the exact brand/model tire you have.
A few of us have found that around 35-36psi on all four tires is a good setting for everyday driving that yields minimal reduced comfort and better grip and treadwear.
To answer your question specificially, the factory pressures should be considered minimum. Dropping 5psi below those pressures will affect treadlife and grip dramatically.
The tire pressure listed is for the lightest load. Look on page 219 in your SLK manual. Are you sure that the MB recommended PSI for your car is 30/30?
I have been putting 4-PSI higher than recommended and my center is wearing faster than the sides. If that happens, it means you have too much air in the tire. Some people that race put more air in the front tire than recommended. My Michelin ZW rated tires on my SLK 320 and SL500 have lasted about 30,000 to 35,000 miles.
If you put less air than recommended, your sides will wear faster than the center. Also you will have a greater chance of hydroplaning.
The best grip is having the greatest contact patch of the tire on the road. If you have less air than ideal, the centers of the tire will not touch the road. If you have too much air, the sides of the tire will not touch the road. It all depends on how much you weight and how much the vehicle weights.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=10
Go here to learn more about tires. http://www.tirerack.com/tires/tiretech/tiretech.jsp
2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
Joined
·
14,798 Posts
Clearly, you can run whatever tire pressure that you like, but....
Brian has pretty much put it all in a nutshell. Much depends on the construction of the tire and in particular the sidewalls.
Typically 35 to 36 psi seems to have worked quite well for most, DrKaligari likes his waaay harder, and apparently triggerfink has had problems with 34 psi in front(?).
With the recommended 30 psi front/33psi rear, pretty much insures that the car will understeer, but have a decent ride. Understeer is considered safer for less the optimal drivers. By raising the fronts you stiffen the overall spring rate of the front of the car, and give the front tires more grip... The car will respond better. You might notice that the book also says something like "That for sportier driving you can raise tire pressure."
It's your choice as to what you want to do, but you really want to monitor the pressures fairly closely while you are experimenting, and in particular in the Spring and Fall when the air temperatures start to vary wildly. That will effect tire pressure as well. Ten degrees temp change will effect the tire pressure about 1 psi.
Personally I run 36 psi all around on my Bridgestone S-03's, race tires start a little lower, and go way up on the track............ In my experiance, 40 psi or more in front tends to make the car feel a little squirlly at speed.
What you want is consistancy, and a fixed pressure helps get that, so yes check you pressures fairly often.
Brian has pretty much put it all in a nutshell. Much depends on the construction of the tire and in particular the sidewalls.
Typically 35 to 36 psi seems to have worked quite well for most, DrKaligari likes his waaay harder, and apparently triggerfink has had problems with 34 psi in front(?).
With the recommended 30 psi front/33psi rear, pretty much insures that the car will understeer, but have a decent ride. Understeer is considered safer for less the optimal drivers. By raising the fronts you stiffen the overall spring rate of the front of the car, and give the front tires more grip... The car will respond better. You might notice that the book also says something like "That for sportier driving you can raise tire pressure."
It's your choice as to what you want to do, but you really want to monitor the pressures fairly closely while you are experimenting, and in particular in the Spring and Fall when the air temperatures start to vary wildly. That will effect tire pressure as well. Ten degrees temp change will effect the tire pressure about 1 psi.
Personally I run 36 psi all around on my Bridgestone S-03's, race tires start a little lower, and go way up on the track............ In my experiance, 40 psi or more in front tends to make the car feel a little squirlly at speed.
What you want is consistancy, and a fixed pressure helps get that, so yes check you pressures fairly often.
1 - 6 of 6 Posts
