SL/R230: Tire Pressure question
10-23-2014, 02:56 PM
#1
Newbie
Thread Starter
Tire Pressure question
So, I was out for lunch and my tire pressure warning came on, so I stop by my local Discount Tire to have it checked out. The guy checks my tires and sure enough, the fronts are running at about 25 PSI and the rears are at 30.
He then checks his computer and based on the size and Service Rating numbers on the tires, he says that they should all be running at 38 PSI. Now, that sounds a bit high to me, and in fact this is the same shop that mounted these tires in the first place and I distinctly remember the numbers they gave at the time we close to 30 or so for the rears and a bit less for the fronts.
Does 38 PSI sound plausible for the recommended pressure? I don't to end up wearing the tires unevenly because of improper pressure.
The tires are as follows:
285/30R20 rear
255/35R20 front
He then checks his computer and based on the size and Service Rating numbers on the tires, he says that they should all be running at 38 PSI. Now, that sounds a bit high to me, and in fact this is the same shop that mounted these tires in the first place and I distinctly remember the numbers they gave at the time we close to 30 or so for the rears and a bit less for the fronts.
Does 38 PSI sound plausible for the recommended pressure? I don't to end up wearing the tires unevenly because of improper pressure.
The tires are as follows:
285/30R20 rear
255/35R20 front
10-23-2014, 03:39 PM
#3
Newbie
Thread Starter
Well, the wheels and tires that came with the car are not what are on it now. Inside the car door it says 27 front and 29 rear. I think the factory wheels are 18's or 19's and these are aftermarket 20's. 38 PSI just seems sort of high for tires of these specs.
10-23-2014, 04:52 PM
#4
The tire wall will tell you the maximum cold pressure. Two of my cars, including my 04 SL500, show maximum cold pressure at 51psi. I run the rears at about 40 and the fronts 37. My Yukon tires are max 44psi and I run them about 40. So, in answer to the OPs question...38psi seems completely reasonable to me. I believe the higher pressures result from the lower volume of air used by the very low profile tires, lower volume but higher pressure. Bicycle tires can easily be 75-100 psi.
Last edited by funymuny; 10-23-2014 at 04:54 PM.
10-25-2014, 06:18 PM
#5
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Weekend: 2010 SL 350 r230 Weekdays: 2018 E220d Coupe
The tire wall will tell you the maximum cold pressure. Two of my cars, including my 04 SL500, show maximum cold pressure at 51psi. I run the rears at about 40 and the fronts 37. My Yukon tires are max 44psi and I run them about 40. So, in answer to the OPs question...38psi seems completely reasonable to me. I believe the higher pressures result from the lower volume of air used by the very low profile tires, lower volume but higher pressure. Bicycle tires can easily be 75-100 psi.
