Tyre pressure check

[sonovagun]

Hi everyone

I am currently running the following tyres on my CL63 AMG:

Rear: 275 35 20Y DUNLOP SP
Front: 255 35 R20 97Y DUNLOP SP

As this is a new purchase for me, I just wanted to know from the audience here how much air pressure (psi) I should keep these inflated on?

The manual (and fuel cap) suggests 38 psi all around, but I’m not sure if that’s a bit too high esp. for both front and rear tyres (?). Any guidance therefore would be much appreciated.

Thank you
Mak

 

[BigJase88]

Go by fuel cap. Mercedes know their car the best.

My fuel cap states 37 psi front 30 psi rear. Which sounds wonky to me but I just go with it. [Not the same car]

 

[OneForTheRoad]

It's your car , mb just offer their recommendations. Put what you like in. Keep an eye on the tyre treads afterwards . Over and below what mb recommend can result in uneven tyre wear.

38psi once hot maybe gets upto 42 psi,so 34psi cold will get you 38psi hot .

 

[whitenemesis]

38psi once hot maybe gets upto 42 psi,so 34psi cold will get you 38psi hot .

Or maybe even higher than 42 as the softer tyre will flex more initially? Under inflation can cause blowouts from overheating over inflation causes excessive wear

 

[pillow]

My CL600 has the same sized tyres and ratings.

I fill mine to 38psi cold. It will raise up to a maximum of 43-44 in my experience.

Another risk of underinflation is cracking the rim.

 

[sonovagun]

Thank you all for the responses.

My CL600 has the same sized tyres and ratings.

I fill mine to 38psi cold. It will raise up to a maximum of 43-44 in my experience.

Another risk of underinflation is cracking the rim.

@pillow - I assume you have not noticed any excessive wear on your tyres as a result? Also, I tend to put my foot on the throttle often (cuz why not ) so I wonder if driving habits have any influence on the recommended tyre pressure..

 

[sonovagun]

It's your car , mb just offer their recommendations. Put what you like in. Keep an eye on the tyre treads afterwards . Over and below what mb recommend can result in uneven tyre wear.

38psi once hot maybe gets upto 42 psi,so 34psi cold will get you 38psi hot .

I am just looking for the optimal pressure that minimises wear / maximises life of the tyre really. And I can only imagine that the MB recommendation is intended to do exactly that..

 

[Bobby Dazzler]

I am just looking for the optimal pressure that minimises wear / maximises life of the tyre really. And I can only imagine that the MB recommendation is intended to do exactly that..

The car manufacturer’s recommendation are the tight starting point but if you are serious about maximising tyre life then monitoring tread depth across the full width of the tyre and adjusting tyre pressures and having alignment checked/adjusted. Many tyres are replaced prematurely because of uneven wear, so avoiding it is the key to maximising tyre life.

Finally regularly using the performance will wear the tyres a more - and it sounds like you will be - so I wouldn’t worry too much about tyre life.

 

[pillow]

Thank you all for the responses.


@pillow - I assume you have not noticed any excessive wear on your tyres as a result? Also, I tend to put my foot on the throttle often (cuz why not ) so I wonder if driving habits have any influence on the recommended tyre pressure..

I'm actually really happy with how little my current set of tyres are wearing.

I don't have much of a lead right foot but we have a lot of 30 > NSL transitions and I do like feeling the torque available

As I say though, far better to need to replace the rubber than trying to fix/replace a cracked rim.

And as @Bobby Dazzler says improper alignment is probably the biggest cause for premature tyre replacement (because of uneven wear)

 

[sonovagun]

The car manufacturer’s recommendation are the tight starting point but if you are serious about maximising tyre life then monitoring tread depth across the full width of the tyre and adjusting tyre pressures and having alignment checked/adjusted. Many tyres are replaced prematurely because of uneven wear, so avoiding it is the key to maximising tyre life.

Finally regularly using the performance will wear the tyres a more - and it sounds like you will be - so I wouldn’t worry too much about tyre life.

Yes that’s relatable what you say about pre-mature tyre replacements. The issue dogged me on my previous car (CLK) even after multiple realignments

I'm actually really happy with how little my current set of tyres are wearing.

I don't have much of a lead right foot but we have a lot of 30 > NSL transitions and I do like feeling the torque available

As I say though, far better to need to replace the rubber than trying to fix/replace a cracked rim.

And as @Bobby Dazzler says improper alignment is probably the biggest cause for premature tyre replacement (because of uneven wear)

Rightly said there - better tyre than rim. And I love the bad boys on these too much to risk it. 38 psi it is!!

 

[Fastcar155]

Hi , checked and adjusted tyre pressure on my C207 5 days ago ( cold ) and set the tyre pressure to 36 psi.

Went for a 10 minute run to collect Iron Rations and the tyre pressures advised on the dash are as follows.

37-38-39-40

37-40 fronts

36-37 rear

 

[Fastcar155]

Hi , checked and adjusted tyre pressure on my C207 5 days ago ( cold ) and set the tyre pressure to 36 psi.

Went for a 10 minute run to collect Iron Rations and the tyre pressures advised on the dash are as follows.

37-38-39-40

37-40 fronts

36-37 rear

37:should read 39