S Class tyre pressures

[Mistermackay]

I have a 2007 S Class with 255.45.R18 tyres. The ride feels hard despite air suspension. Can I safely reduce the tyre pressures to make a more comfortable ride. I only do about 5000 miles per year. What can I safely bring the pressures down to?

 

[MancMike]

The minimum that it says in the fuel filler flap?

My 204 says lowest for under 130 and not fully loaded is 29psi front and 32 rear. It's about 38 front and 41 rear for fully loaded and over 130.

 

[Mistermackay]

The minimum that it says in the fuel filler flap?

My 204 says lowest for under 130 and not fully loaded is 29psi front and 32 rear. It's about 38 front and 41 rear for fully loaded and over 130.[/QU

 

[Mistermackay]

Thanks. I was just wondering if I lower the pressure it may give a less rigid ride.

 

[whitenemesis]

Too low and you run the risk of the tyres over heating. You also run a greater risk of pothole damage.
Drop the pressures to the lower limit on the fuel flap chart. Keep any front to rear differences though.

 

[MancMike]

I get a softer ride with the lower pressures. I wouldn’t go lower. I have accidentally with slow punctures but down to about 20 psi, and it feels wobbly and not good.

As said, the lower the pressure, the hotter the tyres get at speed.

 

[zipdip]

Well running at 28psi will not hurt,I had the same car and size wheels .

 

[190]

The lowest pressures on the fuel flap are for 3 people and some luggage. When I'm not carrying that amount of weight which is most of the time I drop the fronts by 1.4 psi and the rears by 2.9 psi which results in 30.5 psi all round and that noticeably improves the ride. I did make some effort to check it was safe by looking at tyre load tables. By that I mean tables that correlate load with inflation pressure and not the tyre load index such as 89. As far as I could see my pressures were more than safe for the load being carried, I also checked tyre pressures hot after a fast run to make sure they didn't rise by more than 10% due to excessive temperature.

 

[markjay]

I run my W204 C-Class on the lowest figure within the permitted range, which is 36 psi all around. It goes up to 38-39 when the tyres get hot.

If I pump up the tyres any more than that, the ride becomes quite harsh.

The car had 4 good Bridgestone tyres when I bought it, which are still on the car, so until such time that I need new tyres I can't really say if it's a characteristic of the suspension, or of the tyre.

But I can say that my previous W203 C-Class had very supple ride with Conties and Dunlops even when the tyres were pumped to the highest pressure figure within the permitted range.

 

[markjay]

Also... if you run the tyres on the lower figure, expect softer ride but also shorter tyre life.

 

[MancMike]

I run my W204 C-Class on the lowest figure within the permitted range, which is 36 psi all around.

What's different about yours? Different tyre size? Mine are 225/55/16

 

[markjay]

What's different about yours? Different tyre size? Mine are 225/55/16

Mine are 205/55 R16.

225/55 R16 does not sound right for a W204? It should be either 225/45 R17, or 225/50 R16...

 

[markjay]

As, said, I ran My W203 on 35 psi at the front and 41 psi at the rear at all times, and the ride was just fine:

But I run my W204 on 36 psi all around, because the ride is too harsh otherwise:

(also, note the tyre size options for my C180 W204)

 

[MancMike]

Mine are 205/55 R16.

225/55 R16 does not sound right for a W204? It should be either 225/45 R17, or 225/50 R16...

Maybe mine are. Going to check now.

Checked, you’re right 205.

So why are your flap pressures different?

 

[MercedesDriver]

As, said, I ran My W203 on 35 psi at the front and 41 psi at the rear at all times, and the ride was just fine

(also, note the tyre size options for my C180 W204)

Maybe mine are. Going to check now.

Checked, you’re right 205.

So why are your flap pressures different?

Different trims maybe?

 

[zipdip]

Well the op runs a W221 S320 not a Cor E ,and 28psi will be ok,but the op could look at tyres with a bit more give in the sidewalls if he is coming up to a tyre change,I do not want to get into this tyre is best that tyre is poor,but if the op wants a cheap good tyre then the Nexen suv4 is a great tyre on that car it is two ton and that suv tyre suits it.

 

[MancMike]

Different trims maybe?

I don’t see why a smaller engine car on the same sized wheels would have higher pressures, I’d expect lower pressures if anything.

 

[markjay]

So why are your flap pressures different?

Could be many things.

Firstly mine is a saloon... is yours an estate or coupe?

Then, mine has the M274 1.6L Petrol engine with 7G+ transmission... what engine and transmission does your car have?

And last, mine is MY 2013... what year is your car?

 

[MancMike]

W204, saloon.

7G tronic, M272 E30 3L petrol V6.

57 plate, registered in early 2008.

:/

 

[John]

Maybe to do with fuel economy figures?

Higher pressure will yield less rolling resistance improving economy.

Is your car a BlueEffiency MJ?

On age it should be as my car is and is a 63 plate but don't know if they do a C Class BE.