Balance Problem w205

[Srmydone]

Hi Guys,
I’m in a middle of a situation with my C250 W205.
I’ve been driving my car which has 245/40/ R18 Pirelli Pzero on the rear and Fallen FK510 225/20 R18 at the front for more than a year and I never had any problems with balance.
Last week I was due a MOT and I decided to replace the rear tyres, bear in mind I completely forgot the due date which was almost expired therefore, I decided to put ContiSportContact 5 SSR and drove back home.
Two days after I took the car and drove in a motorway and I felt the car completely unsafe to drive above 50miles. When I was overtaking it feels like the rear of the car wants to go left and right, keeps jiggling around, and you have the feeling that the car it’s completely unbalance. If you try to go right and left with the steering wheel the car looks like a puppet.
If I drive 30 / 40 mph I do not have that feeling.
Long story short I took the car back to the shop, we remove all the wheels, balance the wheels again, we did a wheel alignment and I went back to the road . Same problem!
I told the guy that could only be the tyres because it was the only thing that I changed… however the guy does not agree with me and he rang the Continental Engineer or whatever and the guy said that it’s not possible to be the tyres because they were made lat month (08/2020). However the engineer also said that I need to drive at least 100 miles for me to start feeling it as normal? Does this sound legit?
I drove back home with the ContiSportContact 5 SSR at the back and FK510 225/20 R18 at the front and I will do the 100 miles as the engineer said.
I still believe that the problem is those tyres but I would like to ear your thoughts.
Remove the ContiSportContact 5 SSR (less then 100 miles) and put Falken at the back (same as the front ones) or;
Remove the FK510 225/20 R18 at the front and put a ContiSportContact 5 SSR (same as the ones at the back)
Suspension problem?
Thank you

 

[whitenemesis]

Are you sure those fronts are 225/20/R18? Shouldn't they be 35 section tyres and the rears 45 section?
I've never had a 'running-in' problem with new tyres. Are the new tyres directional?

 

[Srmydone]

Are you sure those fronts are 225/20/R18? Shouldn't they be 35 section tyres and the rears 45 section?
I've never had a 'running-in' problem with new tyres. Are the new tyres directional?

Thanks for your reply.

It was a typo - definitely 225/45 R18 at the front and 245/40 R18 at the back
They are symmetrical but not directional.

Any suggestions?

Thanks

 

[unimog]

Are the Falken's SSR tyres? Did the car have SSR tyres on it to start with? Not all 205's had them, my 2016MY did not.

I woud start by checking your wheels are not buckled.

 

[Srmydone]

Are the Falken's SSR tyres? Did the car have SSR tyres on it to start with? Not all 205's had them, my 2016MY did not.

I woud start by checking your wheels are not buckled.

Thank you for your reply.

They are not SSR tyres and the car never had SSR tyres. Also they checked the wheels and they are not buckled.

The issue is when the tyres were fitted the following I though it was the direction that was not aligned so I went to a garage to sort that out and actually mercedes on the same day had a revision and check the car in their machine and no faults were found.

Thanks again.

 

[unimog]

I would say the problem is more related to having two different sidewall strengths on the car. Don't fit SSR tyres if you don't need them, the car is not homologated with them, (all 205 series are not), as you have a compressor and tyre sealant in the boot.

The ride on run flat extra strength tyres is shockingly bad. I binned the same tyres off my Daughters 2018 Mini for that reason. Rides much better on Standard Dunlop Sport Maxx tyres. The S205's I have driven with Bridgestone run flats were shocking. I ran mine on PS4s and Nokian WRA4 and road noise and handling were excellent.

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[Scooby_Doo]

What pressure are you running the rears at ?? When I collected my C250 , new , it had 19's and Continental SSR fitted all round. The ride was hard and skittery and on checking they were set at 265 kpa. Dropped them to 235 kpa and much better.Running non runflat Goodyear Assymetric 3 for the past few weeks and a much better ride.

 

[unimog]

What pressure are you running the rears at ?? When I collected my C250 , new , it had 19's and Continental SSR fitted all round. The ride was hard and skittery and on checking they were set at 265 kpa. Dropped them to 235 kpa and much better.Running non runflat Goodyear Assymetric 3 for the past few weeks and a much better ride.

That is actually a good point, I recall my original Conti’s went bald in the centre when running at the recommended 250kpa cold pressure (upto 280kpa on a long run) after only 5500 miles. I ran 225-230 since that point with no further uneven wear problems. Mine was a none SSR 18” wheel equipped car.

 

[Srmydone]

What pressure are you running the rears at ?? When I collected my C250 , new , it had 19's and Continental SSR fitted all round. The ride was hard and skittery and on checking they were set at 265 kpa. Dropped them to 235 kpa and much better.Running non runflat Goodyear Assymetric 3 for the past few weeks and a much better ride.

The rear tyres are running at 2.5 Bar (365 psi) as per say on fuel tank (actually the guy from the shop said that should be the pressure). This tyres only have 60 miles if... actually when I left the shop I noticed straight away that it was odd to drive however I live near by so I was driving below 40 mph all the way and the tyres where new so... the problem was when I drove it to the motorway... it felt like a whole new car.

 

[markjay]

May I just ask why specifically did you choose SSR for the rear? There are pros and cons for using SSR tyres, but having two run-flats at the rear and then two non-run-flats at the front does seem like an odd choice?

That said, I don't know if this is tne root cause of your issue, I guess the only way to find-out is by swapping the rear tyres either back to your original tyres (if the tyre shop still has them), or to part-worn loaners, etc, and see what happens?

With regards 'bedding-in', I am sure it's a real thing, i.e. tyres do bed-in to some extent, but in my 45 years of driving I have never experienced a tyre shaking when new.... so I think that 'beddibg-in' is unlikely to be the issue in your case.

 

[Srmydone]

May I just ask why specifically did you choose SSR for the rear? There are pros and cons for using SSR tyres, but having two run-flats at the rear and then two non-run-flats at the front does seem like an odd choice?

That said, I don't know if this is tne root cause of your issue, I guess the only way to find-out is by swapping the rear tyres either back to your original tyres (if the tyre shop still has them), or to part-worn loaners, etc, and see what happens?

With regards 'bedding-in', I am sure it's a real thing, i.e. tyres do bed-in to some extent, but in my 45 years of driving I have never experienced a tyre shaking when new.... so I think that 'beddibg-in' is unlikely to be the issue in your case.

To be honest with you I didn't choose the SSR... I only ask for the conti sport 5.. (to be truly honest I was not aware the meaning of SSR until yesterday.)
The Falken Azenis on the front are run-flats.
Before this conti 5 ssr I drove for more that 8 months with FalkenAzenis510 run flat front... and pirelli pzero back run flat and I didn't had a single problem with that...
That's why one my mind the problem need to be this new tyres.

 

[Scooby_Doo]

That is actually a good point, I recall my original Conti’s went bald in the centre when running at the recommended 250kpa cold pressure (upto 280kpa on a long run) after only 5500 miles.

The original SSR on the front of mine had the same problem , 6-7000 miles 2mm middle & 4.5mm sides , hence 235 kpa

 

[Scooby_Doo]

To be honest with you I didn't choose the SSR... I only ask for the conti sport 5.. (to be truly honest I was not aware the meaning of SSR until yesterday.)
The Falken Azenis on the front are run-flats.
Before this conti 5 ssr I drove for more that 8 months with FalkenAzenis510 run flat front... and pirelli pzero back run flat and I didn't had a single problem with that...
That's why one my mind the problem need to be this new tyres.

I'm running runflats on the rear and non runflat on the front and no problems.

 

[markjay]

I'm running runflats on the rear and non runflat on the front and no problems.

I didn't think it will cause a problem... just wondered what's the logic behind this choice of tyres?

(BTW, I got it wrong, the OP actually has run-flats all around).

 

[Srmydone]

I'm running runflats on the rear and non runflat on the front and no problems.

Actually I said to the guy to try that because will be cheaper for me and try with a different set (model/brand) on the back and he said immediately no... He said the best option is to buy the same conti 5 ssr to the front and go from there. He truly believes that the problem is not the tyres because as he said " I sell tyres for 25 years and I never had a situation like this".