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Founding member #7
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Discussion Starter #1
I usually set the tires to the recommended pressure. But now I have winter wheels and tires on. These are the SAME size for front and rear. The dealer just pumped them all up to 37. Shouldn't those fronts still be lower pressure? Or should they all be the same since they are all the same size?
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Tirerack suggests 3-5 PSI increase.
 

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Tire pressure is critical when at highway or higher speeds for long periods of time (higher speed needs higher pressure to avoid overheating and tire failure)(also higher loads, particularly for smaller tires).
Higher pressure means reduced contact patch which equals reduced grip.
Which brings us to your winter tires, winter tires are sensible to overheating on non winter weather so if for some reason you are getting on the highway and its warm you need to pump them up to the higher end of the range.

For normal winter conditions you do not need to worry about it too much, lowering the front will increase grip but since you are not racing around it would be hardly noticeable.
 

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Founding member #7
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Discussion Starter #4
Thanks for both replies. Both make sense. However, I guess what I was trying to find out was if the SIZE difference of the front and rear tires was what was dictating the difference in recommended pressures.

Any opinions on that?
 

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Yes and no, in general smaller tires need higher pressures.
However the difference that you see in the gas door between front and back is actually driven mostly by:
1. Weight distribution
2. Power distribution
3. Desired balance (understeer)
 
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