Non runflats & adaptive suspension

[Luckyone]

I’ve always hated runflats, had to put up with the first set on my other halfs then new 2007 company 320d MSport, the Cerbera had a massively better ride than the the daily driver! She got a 2010 325i SE after that, it was much better but was still hard.

We had a 2012 F13 640d MSport for a while but the ride in that was terrible with runflats on 20”s so we changed to 19”s & non runflats, absolutely transforming the car.

Last year we got a G31 2018 540i MSport with the adaptive suspension. The ride was massively better than the F13 had been so we just drove it as standard for a year on its original runflats. The tyres needed replacing so we decided to get non runflats (Michelin PS5) all round. The ride is smoother but it’s not had quite the transformation I was expecting.

I guess as it wasn’t bad before there wasn’t the same room for improvement but I’ve got a modded E93 335i running lowered suspension & aftermarket shocks (not coilovers) on 19”s with non runflats & it seems to take the smaller bumps in the road better than the G31 with its new non runflats.
I have to crawl over speed bumps in the 335i as there isn’t any big moment available in the suspension to take them where as the G31 can just cruise over them hardly noticing. Big bumps like those are obvious all in the suspension but there’s a cross over point from where the the tyres absorb the tiny bumps to the springs & shocks starting to take over. It just feels like that cross over point isn’t quite right in the G31 with it’s adaptive shocks. They were obviously designed to work only with runflats (& actually did a half decent job of it) so I’m just wondering if anyone has heard of reflash type mods to the adaptive suspension to work better with non runflats?

Its going back to BMW for a service next week so’ll check with them but I can’t really see them wanting to help much…

[hilly10]

I have always hated runflats and with most of my cars mostly purchased second hand I have changed to runflats when the time came to have new rubber. This time having a new X3 it was refreshing to have it come with 20” with non runflats and along with the adaptive suspension the ride is fantastic.

[Luckyone]

Yes BMW seem to have changed their views on non runflats, they were dead again me putting them on the 640d a few years ago. However I spoke to the service manager about them on the 540i & he said yes great idea the non runflats are much better, just make sure you’ve got the tyre inflator kit.

He also said there wasn’t any changes that could made to the adaptive settings, but it would work perfectly well with non runflats tyres as (assuming you stuck to the correct size & ratings).

I guess maybe the PS5s have mildly stiffer side wall to the continentals we put on the 640d….

[hilly10]

Don’t tell me about the tyre inflator kit, I had a puncture two months ago bloody big bolt in the middle of the tyre which wrecked the tyre. BMW guy came out a put a 17” space saver on to get me home. I still had a 18” space saver from my last 5 series with the higher profile it’s neigh on the same size as the 20” X3 wheels going to carry that on long journeys from now on.

[wong]

Maybe runflat technology has improved and closed the gap a little to conventional tyres, when compared to earlier runflats.

[Wills2]

The latest run flats are much better, but everything is a compromise and when you have low profile tyres there is only so much the tyre (RFT or not) and the spring and damper can do.

I have PZ4 rft Pirellis on my car they are very good I also have adaptive air springs and adaptive dampers and active roll bars but on 20" wheels even that set up gets caught out.

[Luckyone]

Actually I take it back saying they didn't make that much difference to the G31, the surface of the roads I had been on were actually in very good condition, just with the odd man hole that is a bit low.

I was on a road I haven't been on for a while that has very broken surface, not pot holed just with the top layer missing all over the place. Last time it was terrible, this time with the non runflats it was hard to tell there was anything wrong with the road! Also I was in a carpark with some silly tiny plastic strip type speed bumps, it used to really crash over those before, now I can hardly feel them.

[Luckyone]

hilly10 said:

Don’t tell me about the tyre inflator kit, I had a puncture two months ago bloody big bolt in the middle of the tyre which wrecked the tyre. BMW guy came out a put a 17” space saver on to get me home. I still had a 18” space saver from my last 5 series with the higher profile it’s neigh on the same size as the 20” X3 wheels going to carry that on long journeys from now on.

Yes sometimes nothing but a spare wheel will do, we cracked a rim on the old E39, I was so glad it had a real full sized spare wheel in the boot, holiday could continue as normal. I have a few different wheel sets or odd ones, it meant I always had something to put on. However BMW changed the PDC at some point between the 2012 F13 & the 2018 G31 so I haven't got anything that fits the G31 now. I will look into space savers, good idea!

[Luckyone]

Wills2 said:

The latest run flats are much better, but everything is a compromise and when you have low profile tyres there is only so much the tyre (RFT or not) and the spring and damper can do.

I have PZ4 rft Pirellis on my car they are very good I also have adaptive air springs and adaptive dampers and active roll bars but on 20" wheels even that set up gets caught out.

I neglected to mention our G31 540i is on 19"s, maybe part of it not being too bad on the runflats...

My friend has got 20"s on his G30, he's happy enough with the ride on normal springs, but he has cracked two rims on it!
Each time causing him a would of pain, many missed business meetings with issues getting replacements wheels & multiple problems with the hire cars not being there & having to return them to stupid places with no means of getting home after. He said he assumed he'd be able to keep driving on the runflats to at least get to garage but after only a few miles the car felt far too unsafe to drive so he just had to stop leaving him stranded for hours.

[JNW1]

Luckyone said:

BMW seem to have changed their views on non runflats, they were dead again me putting them on the 640d a few years ago. However I spoke to the service manager about them on the 540i & he said yes great idea the non runflats are much better, just make sure you’ve got the tyre inflator kit.

He also said there wasn’t any changes that could made to the adaptive settings, but it would work perfectly well with non runflats tyres as (assuming you stuck to the correct size & ratings).

Out of interest did the service manager mention anything about making sure the tyres you fitted were star marked? Given the 540i is X-Drive there are some who'd suggest it's risky to fit anything else but on Michelin's website I can't see they offer any star marked PS5's?

[Wills2]

Luckyone said:

Wills2 said:

The latest run flats are much better, but everything is a compromise and when you have low profile tyres there is only so much the tyre (RFT or not) and the spring and damper can do.

I have PZ4 rft Pirellis on my car they are very good I also have adaptive air springs and adaptive dampers and active roll bars but on 20" wheels even that set up gets caught out.

I neglected to mention our G31 540i is on 19"s, maybe part of it not being too bad on the runflats...

My friend has got 20"s on his G30, he's happy enough with the ride on normal springs, but he has cracked two rims on it!
Each time causing him a would of pain, many missed business meetings with issues getting replacements wheels & multiple problems with the hire cars not being there & having to return them to stupid places with no means of getting home after. He said he assumed he'd be able to keep driving on the runflats to at least get to garage but after only a few miles the car felt far too unsafe to drive so he just had to stop leaving him stranded for hours.

19" or 20" I doubt there is any difference my tyres have a F40/R35 profile which is the same as the 19" I've had on other BMWs, a low profile tyre is low profile no matter the wheel size, my Z4C has 18" wheels but the profile is the same as my 20" on the 7 series as an example.

[Panamax]

Wills2 said:

19" or 20" I doubt there is any difference

I solved my car's harsh ride by going down 1" in rim size. There's lots more "give" in a deeper tyre sidewall. Adding 1/2" to a 3" tyre is a big percentage change.