Tire Pressures
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MBWorld Fanatic!
Joined: Jan 2004
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2004 CLK320
Tire Pressures
For my 2004 CLK320, the recommended tire pressures are 28 front and 29 rear. For driving over 100 KMH, they recommend 30 front and 33 rear.
I have upgraded the tires to 17-inch tires (225-45-17 and 245-40-17) and I am currently running with Pirelli PZero Nero M&S. Since I do mostly highway, I set it to 31 front and 34 rear.
I noticed that many of you set the pressures in the front higher than the rear. Why? I don't really understand what is over-steer or under-steer. What would be better tire pressures for me?
I have upgraded the tires to 17-inch tires (225-45-17 and 245-40-17) and I am currently running with Pirelli PZero Nero M&S. Since I do mostly highway, I set it to 31 front and 34 rear.
I noticed that many of you set the pressures in the front higher than the rear. Why? I don't really understand what is over-steer or under-steer. What would be better tire pressures for me?
Member
Joined: May 2007
Posts: 223
Likes: 3
From: Orlando, Florida, USA
09CLK550Cab 61k miles
I have a 04 CLK500 with your new tire pressures. For the record, the official pressures are 30 front and 33 rear, or 35 and 38 if over 100mph.
That being said, there is a lot of controversy about pressures. I, for one, will run higher in the front and lower in the back. Somewhere around 36/30, which is the opposite order they recommend. My reason: tire wear. At stock pressures, the fronts wear the outside edges badly, and the rears wear out the center rib. My center rib is on the wear bars, and the outer edges has 3/16 or so left. Maddening and expensive!
I saw somewhere online that the best way to test tire pressures is temperatures. On my new fronts, I put 30psi in them and drove 17 miles. At the end, the outside tread was HOT, but the center rib was cold. Next day, but with 36 psi, all tread was about the same temp. This, I believe, indicates equal tread flex/stress, which should be similar to equal tread wear.
Over/under steer. If you in "serious-driving mode," oversteer is fine because if you are going a corner and your back end kicks out, you can correct for it by turning away from the turn, thus avoiding a spin out, which can be seriously dangerous. Understeer is safer - your front end simply doesn't turn as well, so your back end will not spin out. This is good for when the wife drives, but less exciting for you.
That being said, there is a lot of controversy about pressures. I, for one, will run higher in the front and lower in the back. Somewhere around 36/30, which is the opposite order they recommend. My reason: tire wear. At stock pressures, the fronts wear the outside edges badly, and the rears wear out the center rib. My center rib is on the wear bars, and the outer edges has 3/16 or so left. Maddening and expensive!
I saw somewhere online that the best way to test tire pressures is temperatures. On my new fronts, I put 30psi in them and drove 17 miles. At the end, the outside tread was HOT, but the center rib was cold. Next day, but with 36 psi, all tread was about the same temp. This, I believe, indicates equal tread flex/stress, which should be similar to equal tread wear.
Over/under steer. If you in "serious-driving mode," oversteer is fine because if you are going a corner and your back end kicks out, you can correct for it by turning away from the turn, thus avoiding a spin out, which can be seriously dangerous. Understeer is safer - your front end simply doesn't turn as well, so your back end will not spin out. This is good for when the wife drives, but less exciting for you.
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1977 6.9; 2007 CLK350
I, for one, will run higher in the front and lower in the back. Somewhere around 36/30, which is the opposite order they recommend. My reason: tire wear. At stock pressures, the fronts wear the outside edges badly, and the rears wear out the center rib. My center rib is on the wear bars, and the outer edges has 3/16 or so left. Maddening and expensive!
Generally, I start with the factory recommended pressure and add two pounds in the front relative to the rear. For example, my CLK 350 recommends 30/35 for high speed driving. I have been using 30/33. So far wear is pretty even, but I only have 8000 miles on the car.
In my experience, just about every front engined car needs 2-3 pounds more in the front relative to the rear. A lot of cars now recommend 30/30. I would arbitrarily start at 32/30 to see what happens over a few thousand miles.
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Joined: Feb 2021
Posts: 32
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From: Dubai
2005 CLK55
The sticker in my fuel flap says 39PSi, or upto 42 when warm.
But pretty much every tyre site is saying 30 front 33 rear, which is wildly different, for my model and tyre size.
(car is W209 CLK55 with stock 18”).
But pretty much every tyre site is saying 30 front 33 rear, which is wildly different, for my model and tyre size.
(car is W209 CLK55 with stock 18”).
