Dropping wheel size

[Trustmeimadoctor]

I'm sick of the crap ride and cracked wheels on the 20's on my s213

I'm trying to figure out if I should go for 18's or 19's would the 19's be a good enough change or would the 18's be too small

I'd want to stick with merc wheels really

[BlueJ]

I have an AMG line S213 with standard 19" wheels, ride is absolutely fine (great in fact). The 213 is a big car and personally I think 18's would look a bit small, the 19's are bordering on too small from certain angles.

[Trustmeimadoctor]

Hmm I have full air on mine and I've never been happy with the ride so was hoping to gain comfort as the rft and 20's aren't a great

[andy43]

Trustmeimadoctor said:

Hmm I have full air on mine and I've never been happy with the ride so was hoping to gain comfort as the rft and 20's aren't a great

If you've had cracked wheels it could be the runflat tyres (rft?) - their sidewalls are stiffer to support the car without any air in them so any shocks from potholes can get transmitted through to the wheels more than normal tyres.
We had a Mini and going from factory runflats to Toyos on the same alloys was like night and day ride-wise - switching tyres may be worth considering?

[Trustmeimadoctor]

Yeah it's the rft that really ruin it but Conversely if didn't have the rft I'd have been needing recovery more than the 1 i have and needed more tyres I think

I

[TarquinMX5]

On the mbclub forum there have been numerous reports of cracked 19" MB wheels (not necessarily on S213s); if it was me, which it isn't, I'd opt for ride over looks every time, especially with wheels susceptible to cracking and our world-beating roads.

[Trustmeimadoctor]

Down to 17's then

[Ian-27xza]

OP - out of interest, what pressures do you run the tyres at?

The reason I ask is that that my previous S213 had OEM 19s and after 42,000 miles I had zero wheel issues. I've since changed my S213 and the current car has OEM 20s (turbines) and in the 15,000 miles since I've had it I've also had zero wheel issues.

I run the pressures 36 psi front, 42 psi rear. This is towards the mid-upper range, as indicated on the fuel filler cover.

My 19s did run smoother than my 20s but I've found that running the pressures up a bit on the 20s had a positive effect on the overall ride.

A 'cost effective' option might be to buy a used set of OEM 19s with tyres, run them around and see what you think? If you don't like them, just sell them on for probably what you paid for them them (yes, I know ebay messers can be a pain)!!

[Trustmeimadoctor]

210/230 so 30/33 as it says on the flap

Can try it harder but then I'd expect more road noise, harshness and tyre wear

[Ian-27xza]

They look like the minimum pressures for those wheels, although mine indicates 220, front / 230, rear as the minimums, which is 32 psi / 33 psi.

I'd have normally agreed with your logic around tyre pressures and comfort - more pressure = less comfort.

However, I've tried various pressures on the 20 inch wheels and have found that more air actually improves the comfort. I'm not a tyre engineer but what I suspect is happening is that as the tyre pressures increase actually takes some of the strain away from the stiff RFT sidewalls.

Obviously, there is a limit to this and if you run at the very top of the recommended pressures for a heavily laden car (38 psi, front / 45 psi, rear) and the car is actually light you will lead to handling issues, especially in the wet.

[Trustmeimadoctor]

Will try them a bit harder and see

[Trustmeimadoctor]

Well wheel was welded and straightened again last Thursday 14th 230kpa
Took car up to Scotland on the 15th seemed ok no noticeable potholes but rough roads but lower speed 30-50

Back home on the 17th same again noticed it may have been down 5-10kpa

Car not used for a few days and then wife uses it no data

22nd use car it's now 210kpa 30 mile round trip motorway

Yesterday fill tyres up harder as suggested above
Rears are 300kpa maybe 5 miles

Today 225kpa!

Looks like weld has gone again that's the 3rd time ! After doing nothing strenuous with it

I'm fking annoyed as I need to go to the airport again today!

[bolidemichael]

Perhaps in a similar vein to the suggestion above, opt for a spare set of alloys (only MB OEM) in a lower size. If you're patient you can find well priced examples on ebay and gumtree. Then run them with winter tyres and see how you get on.

[Trustmeimadoctor]

That's my plan now I'm just fked off with it I'm driving watching the tyre pressures all the time it's not fun

[DamienCBR]

Ian-27xza said:

OP - out of interest, what pressures do you run the tyres at?

The reason I ask is that that my previous S213 had OEM 19s and after 42,000 miles I had zero wheel issues. I've since changed my S213 and the current car has OEM 20s (turbines) and in the 15,000 miles since I've had it I've also had zero wheel issues.

I run the pressures 36 psi front, 42 psi rear. This is towards the mid-upper range, as indicated on the fuel filler cover.

My 19s did run smoother than my 20s but I've found that running the pressures up a bit on the 20s had a positive effect on the overall ride.

A 'cost effective' option might be to buy a used set of OEM 19s with tyres, run them around and see what you think? If you don't like them, just sell them on for probably what you paid for them them (yes, I know ebay messers can be a pain)!!

Do they still wear evenly and at normal rate?
There is a nasty rut where the A14 joins the top of the M11 across the whole outside lane, went over it the other day, the bang was loud. Not lost any pressure so hopefully ok but thinking if I run them higher as you said it might be a good idea.

[Trustmeimadoctor]

Development for me managed to find a replacement from mercedes official used parts website in Germany basically unused for 340 delivered ordered it last Sunday then yesterday I get a ups notification saying it's getting sent back for some reason so I'm bit pissed to say the least! Cars sat there on a totally flat tyre unable to move

[Ian-27xza]

DamienCBR - Yes, the wear is even across the width, both for the fronts and the rears.