tuffcalc

Attached are the door jam/fuel door stickers showing the inflation pressures for my '11 C63 w/ OEM 19" wheels. They are high (42/42 and 45/48 - not sure why they are showing two different standard load PSI instructions).

I have been running 43PSI all around as a compromise and I am pretty sure in the last week this car has knocked loose all my dental fillings.

If I bring pressures down to 40PSI the ride is much softer and livable. I've searched the forums and can't seem to find any consensus on what is the proper PSI for the 19" OEM wheels.

At 40PSI am I running the risk of a wheel bend? Any other problems? Should I be running at these crazy high 45/48 PSIs? I've never had a car with suggested PSI ratings so high.

I am Jeff

I run 39/42 cold on my 19" HRE's. It's still a harsh ride, but definitely a lot nicer than 42/45 that I was initially running. You should be fine with the slightly lower pressure if you're not fully loading your ride to mass weight capacity all the time.

jvanbrecht

And avoid potholes.. or in my case.. the Entire City of Washington DC.. which is really 1 massive pothole :P

No really though, running lower pressure can be dangerous to both your wheels, and the safety of you and your car and everyone around you. Anyone care to remember the Ford Exploder.. I mean Explorer debacle with Firestone tires, the tires were significantly deflated by Ford to assist in stability (apparently at the original inflation specs, it was prone to rolling over on its own). Running low pressure caused the tire to basically fall to pieces. However, that was closer to 10psi lower. 2 to 5 should not be a problem, but beware wheel dings..

tuffcalc

Other AMG Merc's have 30/35 series tires with doorjambs that claim anywhere from 35-38 PSI. 45+ PSI seems insane... Just trying to find out what is the lower limit to protect from wheel dings.

I guess I'm going to be the test dummy around here

tuffcalc

Does anyone know why the rear tires are spec'd for higher PSI?

jvanbrecht

I understand that, and I am not saying don't do it, I run 38/40 cold on my OEM 18's with Hankook V12's, the downside for me, sidewalls are rather squishy, but at OEM spec of 42, feels like I driving a boat, very very swervy, and not in a good way. at 38/40, that feeling goes away a little, but I would not race the car or take it to a track. just spirited daily driving.

You basically need to do trial and error, till the car feels just right.

side note, I only needed rears, so rather then mixing and matching tires, I picked up a second set, when these are done with the fronts as well, going back to Pzero's or going PS2

tuffcalc

Try out the Pilot Super Sports - I've ran PZero's and PS2's... and these super sports are loads better.

Roswell

I run 40 lbs all the way around w/o problems... very comfy. I believe the 45/48 is recommended with 3+ passengers.

crazy1eye

Yes, they recommend a higher psi when your hauling more passengers & also more cargo.

IMO, try different psi's but check your tread depth every so often to see if your tires are wearing evenly across.

jvanbrecht

The tires in our cars never wear evenly.. the insides always go first

zcct04

They provide two ratings for different load conditions - the first is with 3 people, the second is with five people and luggage. If it's just you on board, a couple pounds less pressure would seem appropriate.

Interestingly, both stickers have a tire size on them, and neither of them looks correct . . .

I am Jeff

You run higher PSI for the rears because they are lower profile than the fronts. 1) is the protect your rims and 2) is for safety for load ratings.

Pickles

39F & 41R is the minimum. If you run any less, ya're in danger of incurring excessive wear on the inside edge of all tyres (like I did!)
Cheers, Pickles.

khmergod

I run 43/45 cold. 48/50 warmed lol. *****es love OEM. jk