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Registered 2001 SLK320
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37 Posts
Discussion Starter #1
In the 8 years I have owned the SLK 320 of 2001 vintage it has always seemed that I got the best tire wear by running 30 psi front and back. The sticker in the gas flap says the correct pressure is 30/33 but what I have been running is at least close to that. At a "B" service last week they told me I should be running 44/40 psi which is what they put in the tires. Looking at the tire it appears that 44 is the maximum pressure allowed. Before I let air out of the tires and go back to my "normal" pressure I'm wondering if there is some ideal pressure for maximum tread life without compromising too much on handling?
 

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Founding Member #2 2008 SLK55 AMG
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19,407 Posts
What type tyres/tires do you have? Summer performance? All-season? Double check the recommended tire pressure from an independent tire/tyre shop. I am running 37psi all around. Latest recommended cold tire pressure was 36/39 both from MB and tire shop, although the original stickers say 32/36.
 

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Registered 2013 SLK55 AMG
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579 Posts
While it's all still relatively fresh in my mind, the instructors at the AMG Driving Academy covered the concept of "contact patch management" involving braking, acceleration and steering -- plus appropriate tire pressure -- to obtain best performance and tire longevity. They were pretty clear that their recommended tire pressures are tuned to the vehicle and should be adhered to. Suspect there will be many people with track and other experience that have a different point of view, but I'm sticking with the posted pressures.
 

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While it's all still relatively fresh in my mind, the instructors at the AMG Driving Academy covered the concept of "contact patch management" involving breaking, acceleration and steering -- plus appropriate tire pressure -- to obtain best performance and tire longevity. They were pretty clear that their recommended tire pressures are tuned to the vehicle and should be adhered to. Suspect there will be many people with track and other experience that have a different point of view, but I'm sticking with the posted pressures.
^^ ditto that.
Personally, I don't understand why you would not stick to the pressure recommended by MB.
 

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Registered 2001 SLK320
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37 Posts
Discussion Starter #6
These tires are Uniroyal Touring tires. The big consideration for me when buying tires is the tread life guarantee and these had 70K which was far and away the best. Most brands that make tires that fit this car have no warranty at all it seems or very little. The life of the tires makes more difference than absolute performance and even at 30 psi have never heard a peep out of the tires going around fast corners. When I have in the past put more than about 30 psi the middle of the tire seems to wear much faster than the edges--especially on the rear ones. I would think that the weight of the car would determine for a given tire size what pressure would make for the most even wear. Anyhow, thanks for the input and believe I'll just go back to 30 all around. Just wish the mechanic hadn't seemed so certain I should be running more pressure.
 

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Mercedes specifies pressures that are a balance between ride comfort, handling, and wear for the tire/wheel size that are supplied as original equipment. The do suggest a higher inflation pressure for extended high speeds. I have a set of Uniroyal Touring GTZ's on my car, suggested pressure works just fine. Go back to suggested pressure or a few lbs. above.
 

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Premium Member 2002 SLK230K
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17,144 Posts
Mercedes specifies pressures that are a balance between ride comfort, handling, and wear for the tire/wheel size that are supplied as original equipment. The do suggest a higher inflation pressure for extended high speeds. I have a set of Uniroyal Touring GTZ's on my car, suggested pressure works just fine. Go back to suggested pressure or a few lbs. above.
I agree, MB's numbers are a safe average based on original tires. Manufacture recommended pressures are based on tire wear and their construction plus the tire rating (type of compound used) Some tires have a softer rubber verses a harder rubber. I believe the higher the letter the softer the rubber which means less milage before replacement.
I prefer the softer rubber for grip.
 

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Registered 2011 SLK300
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427 Posts
I would think that the weight of the car would determine for a given tire size what pressure would make for the most even wear. Anyhow, thanks for the input and believe I'll just go back to 30 all around. Just wish the mechanic hadn't seemed so certain I should be running more pressure.
That is exactly what determines tire pressure for mileage and safety. Manufacturers may compromise a bit for ride comfort, but remember the Firestone fiasco a few years back when Ford lowered the pressure for their big SUV's? Too much compromise for ride comfort. Stick with the 30 psi if it works for you.
Bus and truck tires are inflated to strict guidelines for long tire life and safety. The DOT cops pull them over all the time to check tire pressures which also vary by tire temperature. If the tire is supposed to have a cold inflation of 105 psi and 113 psi at a tread temperature of 130ºF then if they are below those values they get ticketed for an overloaded vehicle. I've been checked, but not ticketed.
 

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Registered 2012 SLK55 AMG w/P30
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3,492 Posts
I'm running 36/40. I find a slightly higher tire pressure gives me a firmer ride and a little bit better handling. Especially since this car is notorious for tire edge wear this should (hopefully) help to ameliorate it.
 

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Premium Member 2013 SLK250
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2,420 Posts
If you are using the stager wheels and tire size that are different on rear than on the front you do not have the full 70k warranty. See below

Treadwear – Mileage Warranty Coverage for Uniroyal® Passenger and Light Truck Tires Some Uniroyal® Tiger Paw® and Laredo® tires are covered by a manufacturer’s limited warranty for treadwear, for six years from the date of purchase. For the mileage warranty associated with a specific tire line, please see your Uniroyal Tire Dealer or visit us at www.uniroyaltires.com/care. Some vehicles come from the vehicle manufacturer with “split fitments”– meaning different size tires on the front and rear axles. Because these tires cannot be rotated as recommended by Uniroyal, the mileage warranty on each rear tire will cover half the number of miles as the standard mileage warranty for that particular tire design
 

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Premium Member
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307 Posts
I did wonder if my low profile whiz wheels needed a slightly higher tyre pressure but my tyre garage said keep them standard but when I checked them after replacing all four I found them all set to around 40psi so no prizes for them!

I am back on OEM and will keep a look out for tread wear

I am used to 12k miles on the front of my Peugeot front wheel drive diesels if I was lucky
 

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Registered 2001 SLK320
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37 Posts
Discussion Starter #13
Why am I not surprised that there would be enough extra-fine print so that they could void half the warranty? However, if these tires get 35K miles they will have done much better than any tires I've tried so far. At least after more than a year and 10K miles there is no detectable wear. After much thought have gone back to 30/30 psi which is at least close to the OEM recommendation.
 
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