[sanch8]

I finally got rid of my oem square Pirelli a/s 225/40 19 on my 330i and replaced them with Michelin ps a/s 4. Ran the pirelli's for 36,000 km exactly and they still had another 6-8k left in them but I couldn't wait any longer.

Pros: as expected the ride is much better and I am not feeling every single road imperfection in my butt and jaw. I almost never used my adaptive suspension in the sport setting because that just made the suspension too harsh and I didn't want the car to develop excessive creaks or damage the rims. But the sport setting on the dampers is now actually usable and a lot of fun.

Cons: imo during spirited driving the turning doesn't feel as sharp and I can't place the tires during turning with 100% accuracy. I also get this feeling of understeer with fast turns until the tire suddenly bites and I have to make a correction to avoid an oversteer. The G20 330i is not exactly known for steering feel but whatever little feedback I got with the run flats is now gone.

Also, the tpms is asking me to put in 38psi front and 46psi at the back. I think it was 2psi less for Pirelli run flats. Is this normal?


Have others had a similar experience when switching from run flats to go flats?

[G30M]

yes numerous tyre testers have said run flats have a sharper turn response due to extremely stiff sidewall.

if i ditch my run flats i'm going from 225 to 245/255 front. rear already at 255.

[HighlandPete]

Originally Posted by sanch8

Have others had a similar experience when switching from run flats to go flats?

Yes, this applies right back to the early days of RFTs, on the E9x models.

We hear many users saying "chalk and cheese", "night and day", difference to the ride quality and comfort improvement, but not too many share the negatives. The differences shouldn't be so marked these days, as RFTs are not as stiff as they were with first and second generation RFTs.

Before I changed the RFTS on my E91, I talked with a couple of tire shops I respected and got their opinion. One stated there were compromises, it's not all good. One guy shared his customer's experiences on doing so. How one customer went for a drive, was soon back and asked to fit the RFTS back on his 3-series. He had lost the precise chassis and wanted it back.

I didn't like the RFT ride on my car, so I took a more cautious route, got another set of rims and UHP tires to experiment. Yes, the comfort improved on my E91, but the car was compromised, now needing some suspension changes. Damping was too soft and handling compromised. I changed the dampers and got the best of both worlds, comfort and improved handling.

I'd experiment with pressures, see if there is a good compromise.

[HighlandPete]

Originally Posted by G99M5

yes numerous tyre testers have said run flats have a sharper turn response due to extremely stiff sidewall.

if i ditch my run flats i'm going from 225 to 245/255 front. rear already at 255.

That will make the turn in even more numb, and you will lose precision. Or are you planning to change (widen) rims as well?

[G30M]

Originally Posted by HighlandPete

That will make the turn in even more numb, and you will lose precision. Or are you planning to change (widen) rims as well?

I am afraid of that, I can believe how precise the 225 is for such a heavy case at such high speeds. hope my tyres will last for a bit, but when it's gone or damaged I might experiment if I can find the right tires, for better or worse.

19x8.5 or 18x9 (roads here are full of potholes)
I thought the low profile of the 255 35 19 will offset the narrow rims while provide some rim protection.

Or I might just use 245-255/40 18 on the 18x9.

[G30M]

Originally Posted by HighlandPete

Yes, this applies right back to the early days of RFTs, on the E9x models.

We hear many users saying "chalk and cheese", "night and day", difference to the ride quality and comfort improvement, but not too many share the negatives. The differences shouldn't be so marked these days, as RFTs are not as stiff as they were with first and second generation RFTs.

Before I changed the RFTS on my E91, I talked with a couple of tire shops I respected and got their opinion. One stated there were compromises, it's not all good. One guy shared his customer's experiences on doing so. How one customer went for a drive, was soon back and asked to fit the RFTS back on his 3-series. He had lost the precise chassis and wanted it back.

I didn't like the RFT ride on my car, so I took a more cautious route, got another set of rims and UHP tires to experiment. Yes, the comfort improved on my E91, but the car was compromised, now needing some suspension changes. Damping was too soft and handling compromised. I changed the dampers and got the best of both worlds, comfort and improved handling.

I'd experiment with pressures, see if there is a good compromise.

Hard to know, I'm referring to current generation tyres.

The side wall of the 8 inch contact patch length must be strong enough to hold up upwards of 2000lbs when you turn your car and shift all the weight onto the front right at 50mph when fully loaded.

No way if the side wall is not stiff that it can do that. There will be some noticeable difference in certain situations.