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Discussion Starter #1
When I got my car, I immediately put new Goodyear Assymetric MO ‘quiet tyres’ on all four corners. I had this car in for its service yesterday and all four tyres are wearing slightly more on the inner and outer edges than the centre. I had the geometry set up by a professional company (Not Quack Fit et al!) and I regularly check the pressures to the recommended levels.
Does that suggest that I should increase the pressures? Or... is that normal?
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Inner-->normal, especially on fronts.

Inner & outer-->under inflated.

Check on the gas filler door (inner) for correct pressures. Use the lower values on the sticker.
 

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6007.us
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Keep in mind that the proper inflation for a tire depends on the tire characteristics, rim, suspension geometry, inflation, and driving habits. That said inner AND outer generally means either too narrow a tire for the rim or underinflation or both.

To determine proper inflation for a street car I usually take the weight on each end, multiply by .625, and divide by the load rating of the tire. Then multiply by the inflation pressure at the load. For more spirited driving I use .75. For racing, 1.0 and a bit of decambering from stock. Can also tell by the amount of roll visible on the sidewall of the front tires.

For wheels on a street car I look for a rim that is the same width and the tread. For racing, the same width as the section. e.g. for really hard driving or racing and a 245 tire I'd want a 9.5-10" rim.

Car will tell you a lot about what is going on if you listen.
 

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Discussion Starter #4
Hi! Well that’s the dilemma I face because I inflate to the lowest recommended pressures as shown inside the filler cap!?!?
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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I always use more than the minimum

says 32 front, i use 34
says 35 rear, i use 36
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Depends on how firm a ride you want. When I got her, dealer had it set at the maximums on the decal. Little did I know.

Going over r.r. tracks I thought my fillings would fall out. Adjusted to min on the decal and it's a lot softer (so-to-speak) now.

Higher psi's are for "racing speeds" which I never do :wink:
 

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Premium Member 2013 SLK350
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Methinks in the hot/dry weather, your tires need a tad under-inflated (32-36psi), but in frigid/low temp, your tires need to be a tad over-inflated (36-40psi). Chilly temps reduce tire psi so adding a couple more should keep the tires properly inflated for your driving style. Will also depend on the size of your tires and the max pressure they can handle.
 

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6007.us
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In general I go up a size or so. For example my SLK320 came with 205/225s I went to 225/245s. In cars with ABS the important thing is to keep the front and rear diameter the same. The actual size does not really matter as long as they have an appropriate load rating. Nice thing about going up a size, when you calculate the load vs psi, with a slightly larger size you can drop the psi a bit for a softer ride.

ps I kept the stagger because the tires were within a dollar or two for both but is more for styling than performance.
 

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Registered 2005 SLK350
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Is your vehicle lowered? Generally SLKs come with quite a bit of camber, and more so for those with lowered ride height. If the uneven tyre wear concerns you may be you can consider installing one of those after market camber kits to improved that. Actually there are bolts to do that for the front from Mercedes, but only to very little extent
 

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Discussion Starter #10
Is your vehicle lowered? Generally SLKs come with quite a bit of camber, and more so for those with lowered ride height. If the uneven tyre wear concerns you may be you can consider installing one of those after market camber kits to improved that. Actually there are bolts to do that for the front from Mercedes, but only to very little extent
No, mine is spec'd with comfort suspension. It's not a big discrepancy on wear, but the centre of the tyre on all 4 is showing less wear. I've just put a couple more psi in, as given the soft ride, it's made no difference to the ride. I'll see how I get on.
 

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Whats needed is Camber and Caster adjustment - and it does not exist.
Only setting change is Toe in or Toe out. See K-Mac.com the manufacture
front and rear adjuster kits to allow to adjust tire contact angles
 
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