Tire pressure adjustment for + sizes
07-30-2014, 06:12 PM
#51
It will likely fail
Must have a 10-20% margin for accel, both linear and angular, impulse (bumps), loss of strength due to fatigue, etc.
That is why MB REQUIRES 41
If you think advising people to run 36/36 on a 91 LI when MB requires 41/45 on an even higher 95/94 LI is sound advice you obviously do not understand
They are not pulling numbers out of their butt like you lol
Last edited by Ingenieur; 07-30-2014 at 06:17 PM.
07-30-2014, 06:53 PM
#52
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2011 C63 AW
I wish I'd seen this thread a couple months ago. I set the tires at the factory spec of 41/45 I think, which turned out to be 43/47 when warm. THAT SUCKED!
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
07-30-2014, 07:01 PM
#53
I wish I'd seen this thread a couple months ago. I set the tires at the factory spec of 41/45 I think, which turned out to be 43/47 when warm. THAT SUCKED!
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
Then saw the door flap 39/39, much better
The I noticed when CPO'ed the dealer put 245/265 vs oem 235/255
The LI's are much higher: oem 95/94 vs 97/97!
So to get the same load as oem 40/42 in the middle min/max I could set them at 37/36
I settled on 37/38 which is a vast improvement in ride and wearu
07-31-2014, 12:36 PM
#54
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W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, C5 Z06 & IS300 race cars, EQE 4Matic+ on order
Ingen is right on this - you do not want to under-inflate your tires. If you can figure out the actual vehicle weight and load and do the math for the load index, then all the power to you. Mercedes is always going to assume the worst-case scenario and add a 15-20% safety margin so that's how you end up with the high reecommended pressures on the fuel door. Having said that, a slightly over-inflated tire (while providing a harser ride) is much safer than an under-inflated tire which is prone to overheat due to the sidewal flexing and burst (Ford Exporer / Firestone issue). If in doubt, put more air in rather than less.
IMHO you're all very much overthinking this whole LI and rating thing. If you are running OEM tire sizes, put in what the fuel door says and just drive the damn thing. You bought a C63. If the ride is too harsh, buy a freaking Cadillac instead and stop with the moaning. But, just to add more fuel to the fire, not all "same" tires are the same. In fact, the OEM Contis or Yokos that come on the C63 are differnt than the regular Contis / Yokos of the same model/size. There is that little pesky "M0" suffix, which means they're made specifically to MB's specs that are different from the regular batches. Same goes for Porsche tires - they use the N-spec tires, which must meet more stringent standards than the identical regular production tire. The M0 tires do not list the actual load ratings - they only say that they are XL rated. Have fun with that one now...
IMHO you're all very much overthinking this whole LI and rating thing. If you are running OEM tire sizes, put in what the fuel door says and just drive the damn thing. You bought a C63. If the ride is too harsh, buy a freaking Cadillac instead and stop with the moaning. But, just to add more fuel to the fire, not all "same" tires are the same. In fact, the OEM Contis or Yokos that come on the C63 are differnt than the regular Contis / Yokos of the same model/size. There is that little pesky "M0" suffix, which means they're made specifically to MB's specs that are different from the regular batches. Same goes for Porsche tires - they use the N-spec tires, which must meet more stringent standards than the identical regular production tire. The M0 tires do not list the actual load ratings - they only say that they are XL rated. Have fun with that one now...
Last edited by Diabolis; 07-31-2014 at 12:41 PM.
07-31-2014, 12:38 PM
#55
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I wish I'd seen this thread a couple months ago. I set the tires at the factory spec of 41/45 I think, which turned out to be 43/47 when warm. THAT SUCKED!
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
Last edited by Diabolis; 07-31-2014 at 12:43 PM.
07-31-2014, 03:06 PM
#56
I wish I'd seen this thread a couple months ago. I set the tires at the factory spec of 41/45 I think, which turned out to be 43/47 when warm. THAT SUCKED!
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
The tires were like balloons, the ride ultra stiff, and I got complaints from passengers. I discovered the gas door and went with a 38/38. Love it! Much softer ride and it just seems better all around.
are you on oem spec tires?
07-31-2014, 04:21 PM
#57
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Is there any harm in running tires and/or pressures that exceed the load required for the car? I've always been carful to get enough, but never thought there was much of a downside to having a setup that exceeds the load requirements of the car.
07-31-2014, 04:40 PM
#58
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Provided that you don't overinflate the tires past their maximum rated pressure (usually 50 psi cold - it's somewhere on the sidewall) and the possibility that you may get somewhat uneven tire wear due to over-inflation, the anser is no. It simply means that your tires are able to safely support a heavier vehicle or load.
07-31-2014, 05:29 PM
#59
Ride will be harsher
Tires will wear in the middle
Handling will suffer, less contact patch and the shape changes from the lateral to the direction of travel
07-31-2014, 07:05 PM
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2011 C63 AW
My gas filler door says 38/39 for light loads.
No chance of a blowout where I'm set at. If you wanna stay above 40lbs by all means do so, but I feel better at 38/38 and the tire wear is spot on. Most of the time, it's just me on a joy ride during the weekend. 43/47 warm is brutal on your fillings, back, and suspension IMO. I have a lot of bad roads around me. This car is meant for autobahn.
No chance of a blowout where I'm set at. If you wanna stay above 40lbs by all means do so, but I feel better at 38/38 and the tire wear is spot on. Most of the time, it's just me on a joy ride during the weekend. 43/47 warm is brutal on your fillings, back, and suspension IMO. I have a lot of bad roads around me. This car is meant for autobahn.
