Heisenberg

Since a lot of forum members have put 20" wheels on their CLS, I was wondering what they are using for their tire inflation pressures ?

I replaced the 19" stock wheels with 20" forged 3pc Vellano VSM. Tires are the same type as stock, Pirelli PZero Nero, but in 255/30-20F & 305/25-20R sizing. So far I have stayed with the factory recommended pressures for two passengers as written on the inside of the fill cap, except that I add 2-3psi over their specified cold tire pressure to account for the heat here in Arizona. Lately it's been ranging from 90 at night to 110 during the day

With the lower profile tires is there any need or reason to go higher or lower with the pressures ?

I check the tire pressure about every two weeks since the car does not have TPMS installed, and by the time I see the 3" sidewall bowing out from low pressure it may be too late. Besides being expensive, the 305/25-20 rear tires are in very short supply. I'm actually going to order one just to keep around in case one suffers irrepairable damage.

clos

I had this problem with my e320. Low profile tires need to be checked constantly, I believe even if you would of had the TPMS it doesn work well with aftermarket wheels. I just noticed my tires are running low and they are stock I can't imagine what it would be like with the 20's. Here with all the constant street construction you have to be extremely careful not to damage the rim becuase tire pressure is low.

I've heard so many different things on recommended tire pressure. Keep it lower than recommended keep it higher than recommended. Every one has a different opinion. I would go with what the manufacture recommends and adjust due to your extreme heat in Arizona.

another issue that can become a huge debate.

Clos

rflow306

With the 20's i tend to run about 40 lbs all the way around. Especially with a 30 or 25 series tire. The primary reason is to protect your wheels a little more. Not the best set-up for handling but nothing is more aggravating than bending a wheel. I check all four corners every three to four days just as a precaution. Like you said these tires are not easy to come by, i have 285/25- 20's on the E and they are always on back order. I destroyed one tire because of a flat, i drove 15 miles and did not feel a thing.