More tyre advice. BMW X4 F26.

[PhilGibson]

Hi all, looking for some peace of mind if you can help.

I posted about a month ago about charging from run flat pirelli p zero tyres to non run flat tyres.

My tyre size is
245/45/R19 front
275/40/R19 back

I took the plunge after many hours if research and conversations with BMW, I purchased pirelli p zero in the non run flat version, as they were the only set I could find in my tyre size non run flat, so basically a * marked like for like replacement.

So I had them fitted on Friday, then did a drive from Kent to Birmingham over this weekend.

All I can say is the ride quality is much worse than before feel every bump, every shock through the cabin, rumbling feedback through the steering wheel, feel like I am on a roller coaster waiting to be thrown about by the car again.

I am hoping this is just the tyres needing a bedding in period. I have also tried reducing the pressure slightly, but it's still not helping.

Do you think this could be something else, as I spent £750 on the new tyres and I am getting close to putting the old run flats back on just to return to normal!!

Help appreciated.
Cheers.

[Pica-Pica]

My understanding is that, now, runflats and suspension are tuned as a system. It may be folly to change one element of a system without consideration of the system as a whole.

[rassi]

You should at the very least have a slightly better comfort and less road noise, but not stiffer and crashier ride. They didn’t manage to mix up the wider wheels front to back or mount the front tyres on the wider rear wheels and vice versa?

[SAS Tom]

Have you tried changing the pressures to suit?

[PhilGibson]

Tyres are on the right wheels front and back, no issue with that.

The back was 38 psi, the front was 37 psi.

I moved the back to 35 psi front 32 psi which is slightly less than the recommended. So that's not the issue.

Confused!

[mekondelta]

Where are you getting the pressure recommendations from? Could it be you're using pressures determined for RFTs whereas non-RFTs are different? Just guessing..

[PhilGibson]

Tyre pressure on the door suggests 38 psi back 35 psi front. So I have reduced just under this recommended for run flats.

[anonymous-user]

If anything a non run flat would need a higher pressure than an RFT.