Tire pressure question: Michelin Pilot Super Sports
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CLK 350
Tire pressure question: Michelin Pilot Super Sports
Sorry if this belongs in the sticky tire/wheel thread but didn't seem like the right home for this. On my 2009 CLK 350 cabriolet I just put on new Michelin Pilot Super Sports all around (stayed with the stock wheels/sizes). My brother in law has those tires on his IS350 and was raving about them and they get top reviews everywhere.
I took the car to a top local alignment shop for this work since I wanted to take care of a persistent pull to the right that the car has had since I bought it in 2011. They put in alignment correction bolts on both the left and right side and while it's only been a day since I got the car back, the pull seems to be substantially gone.
My question is about tire pressure. The shop set the pressure to 36 in the front, 40 in the rear, markedly higher than the recommended/stock pressure. They acknowledged that but said it was the right pressure for this tire for ongoing wear and handling, saying I could drop the pressure if I felt the ride was too harsh. It's certainly harsher than it was but I was planning to let the tires break in before deciding to drop the pressure. What do you folks think about those pressure settings? Go with the shop recommendation?
I took the car to a top local alignment shop for this work since I wanted to take care of a persistent pull to the right that the car has had since I bought it in 2011. They put in alignment correction bolts on both the left and right side and while it's only been a day since I got the car back, the pull seems to be substantially gone.
My question is about tire pressure. The shop set the pressure to 36 in the front, 40 in the rear, markedly higher than the recommended/stock pressure. They acknowledged that but said it was the right pressure for this tire for ongoing wear and handling, saying I could drop the pressure if I felt the ride was too harsh. It's certainly harsher than it was but I was planning to let the tires break in before deciding to drop the pressure. What do you folks think about those pressure settings? Go with the shop recommendation?
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Your car should have two ranges for tire pressure - one for normal driving, another for >100mph. Since I do often drive in the 90-100mph range on the highway, I split the difference, which puts me right around 36 front and 40 rear. It gives me a good combination of handling and comfort.
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2008 CLK550 Cab
I have an '08 with 19", and nothing on my fuel door. Just the range on the door jamb. Pretty sure it's 38/42. That's what I run. Rodney, where the heck can you run nearly 100 on the highway and not fear a huge ticket? I don't even do 100 across Nebraska or Kansas unless passing. Maybe I'm just chicken in my old age. I usually cruise in the mid to high 80s.
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CLK 350
Thanks everyone, sounds like I'm in the right ballpark. My brother-in-law just verified that he runs 36/36 on his IS350 so will keep it where it's set for now. I had the same question for Rodney, I've hit 90 on I5 here in California but won't keep it there for long, I'm more in Yidney's 80's range. But I'm an old guy myself.
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From: Atlanta Metro
2008 clk550 - Navigator - Frontier
Since about 2009 I've set mine to 40/41.. I can't recall how I calculated those numbers.
Like ellefritz says "I'm an old guy" and generally cruise on the open highway at speed limit + 7-10; but like you I sometimes run into the triple digits. It doesn't take long to get from 80 to 100+..
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
The recommended pressures do not adequately account for load or lack of it. My car has stock 17" Elegance staggered wheels. It runs 99% of the time one up.
For even wear & comfort I run 2.3 bar front & 2.1 bar rear (ie 33psi front & 29 psi rear). Otherwise rears wear in the middle of the tread. (over inflation)
This is with OE Conti SC3's. I suspect with Michelin construction a little harder will be required especially at the front.
About to fit new Michelin boots.
For even wear & comfort I run 2.3 bar front & 2.1 bar rear (ie 33psi front & 29 psi rear). Otherwise rears wear in the middle of the tread. (over inflation)
This is with OE Conti SC3's. I suspect with Michelin construction a little harder will be required especially at the front.
About to fit new Michelin boots.
Last edited by Glyn M Ruck; Jul 10, 2014 at 03:44 PM.
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As for the speeding, our suburban interstates around here are a posted 70mph, but unless it's rush hour, the nominal speed is 80mph, and even then you may feel you are slowing down traffic. There are stretches of 6-lane here with a solid concrete median barrier (so no flip-flopping) and limited interchanges or overpasses, so there's nowhere for the cops to hide. i have one such stretch on my way to work. I don't go in until 9AM so there usually just a small amount of traffic running 85-90, so I hop in the left lane and punch it. I've never hit the speed limiter of 135mph, but I have come close. Oh, and I run with a Passport 9500IX and one foot ready on the brake. 
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CLK 550
I lost 3 tires this past winter due to running them based on what is stated on the fuel door. At that pressure, your tire hits the rim if you hit even a small pot hole. So, I run 45 psi on all tires. I took the door number + the tire number and divided by 2 to get 45. Car runs great and I can hit a bump without worry.
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Wow, if I run the >100mph pressure, every bump in the road is a bone jarring experience and the top rattles and the cowl shakes. This is why I split the difference. And this is on 17" rims. I can't imagine how bad the 18" rims would be.
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From: Atlanta Metro
2008 clk550 - Navigator - Frontier
IMO - the treads handle rough road and bumps better than the sidewalls. Besides that, I like curves (not those
). I want those sidewalls to stay as vertical as possible when laying into and powering out of a curve.I guess, within some range, it is a matter of preference....
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From: NJ
CLK 550
I am running 17" and did not really notice a difference. Normal bumps are fine.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Tyre pressures should be dependant on carcass construction & load. There are no ways a Michelin PS Series tyre & a Conti SC can run at the same pressure all things remaining equal & give even wear. Tyres should wear evenly across the tread especially on the rear if correctly inflated. Front's can show some shoulder wear if you are an enthusiastic driver.
I agree for track days etc. bump the pressure but not for day to day driving or you are going to suffer over inflation wear. (centre of tread)
I agree for track days etc. bump the pressure but not for day to day driving or you are going to suffer over inflation wear. (centre of tread)
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CLK 550
Tyre pressures should be dependant on carcass construction & load. There are no ways a Michelin PS Series tyre & a Conti SC can run at the same pressure all things remaining equal & give even wear. Tyres should wear evenly across the tread especially on the rear if correctly inflated. Front's can show some shoulder wear if you are an enthusiastic driver.
I agree for track days etc. bump the pressure but not for day to day driving or you are going to suffer over inflation wear. (centre of tread)
I agree for track days etc. bump the pressure but not for day to day driving or you are going to suffer over inflation wear. (centre of tread)
Last edited by Mercedes-Benz; Jul 13, 2014 at 03:56 PM.
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From: Atlanta Metro
2008 clk550 - Navigator - Frontier
There are probably a number of ways to check if your tread are making contact as they should.
One way is to put some chalk (or whatever that will easily come off when the tire is in use) on the tire treads and roll onto a piece of white paper. It will leave a tread print and you can tell if there are treads not in contact and the length and width of the contact.
I just use a flashligh (or my work light) pointed at the front side of the tire and the garage floor and look at the back side (trailing) of the tread at the floor looking for even amounts of light between the treads and between the edges of the tread and the start of the sidewall.
I just like the tires to stand on the treads and for the sidewall to be as vertical as possible without having it roll like the first wheels fashioned from stone.
One way is to put some chalk (or whatever that will easily come off when the tire is in use) on the tire treads and roll onto a piece of white paper. It will leave a tread print and you can tell if there are treads not in contact and the length and width of the contact.
I just use a flashligh (or my work light) pointed at the front side of the tire and the garage floor and look at the back side (trailing) of the tread at the floor looking for even amounts of light between the treads and between the edges of the tread and the start of the sidewall.
I just like the tires to stand on the treads and for the sidewall to be as vertical as possible without having it roll like the first wheels fashioned from stone.
