2012 C300 Recommended Pressure Tire seems high
10-20-2014 | 12:01 PM
#1
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C300
2012 C300 Recommended Pressure Tire seems high
The door panel calls for 34 psi front and 42 psi rear. I guess one needs to follow the recommendation, but doesn't that seem kind-a high? I have owned earlier C300 and the pressures were lower. Just want to make sure.
10-20-2014 | 01:59 PM
#3
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Joined: Jan 2009
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From: Silicon Valley, California
Factory ordered 2012 MB C350 w/Dynamic Handling Package
The base (minimum) pressure is what is shown on the gas cover and is determined by the estimated load on the car. This is why a C63, C350, C300, C250 will have different values because the load is distributed differently (example..a C250 should have lower PSI values than a C63 because it is lighter). Anything above that is determined by the theoretical maximum speed you will be travelling and the rating of your tire at the time you are doing it.
My car at the time of purchase had H-rated tires. H-rated tires can only safely go as fast as 130MPH, hence why the stock ECU limitation is set to that value.
The +3 PSI value Mercedes recommends is based on speeds above 100 MPH. If you are NEVER going to travel that fast, the base PSI should suffice, however as a safety precaution, I always recommend setting the PSI to match the highest theoretical speed your car can travel.
For a more precise chart...look at this link...
http://www.tirerack.com/tires/tirete...adj_Hspeed.jsp
The link will show you that while an H-rated tire will do 130mph...you'll still need to add +5 PSI to the base OE value to do it safely. A Y-rated tire however, can travel at that same speed without the PSI increase because of the higher heat tolerance.
So in summary...a good set of rubber will net you the following even if you never plan to take it to the track...
#1 Better braking (reducing braking distance is priceless).
#2 Better handling (emergency lane changes anyone?).
#3 Better acceleration (need to get in front of someone while waiting for a stop light?)
#4 More comfortable ride (because you can set it to a lower PSI).
#5 Lower chance of a tire blowout due to under inflation (because of higher heat rating).
#6 Higher theoretical top speed (if paired with an ECU update).
My car at the time of purchase had H-rated tires. H-rated tires can only safely go as fast as 130MPH, hence why the stock ECU limitation is set to that value.
The +3 PSI value Mercedes recommends is based on speeds above 100 MPH. If you are NEVER going to travel that fast, the base PSI should suffice, however as a safety precaution, I always recommend setting the PSI to match the highest theoretical speed your car can travel.
For a more precise chart...look at this link...
http://www.tirerack.com/tires/tirete...adj_Hspeed.jsp
The link will show you that while an H-rated tire will do 130mph...you'll still need to add +5 PSI to the base OE value to do it safely. A Y-rated tire however, can travel at that same speed without the PSI increase because of the higher heat tolerance.
So in summary...a good set of rubber will net you the following even if you never plan to take it to the track...
#1 Better braking (reducing braking distance is priceless).
#2 Better handling (emergency lane changes anyone?).
#3 Better acceleration (need to get in front of someone while waiting for a stop light?)
#4 More comfortable ride (because you can set it to a lower PSI).
#5 Lower chance of a tire blowout due to under inflation (because of higher heat rating).
#6 Higher theoretical top speed (if paired with an ECU update).
Last edited by edgalang; 10-20-2014 at 02:37 PM.
