BMWN

Guys,
I'm not saying that RF are better than PS2 since I havent tried them yet.
My car has 1600 miles as of today so tires are pretty much new. It's just the fact that some people switch them right away its just $$ you're throwing out, I should have mentioned before that ride RF untill they are gone then make your choice. Now about suspension and tires I agree that tires play role witht he whole performance thing but generaly it's the grip that they are providing and how fast they warm up. With that being said ride could be harsher with certain type of tires like in our case its RF due to stiffer side walls which is obvious, but its not terrible ride like some1 stated earlier in other posts. I think BMW put them on for reason but who knows, hearing only positive things about PS makes me want to buy them but not untill my RF are gone. Enjoy the ride folks,
my assumptions came from ridding motorcycles and I've done tons of mods to my Suzuki SV650S that has only original frame and engine on it.

colejl

Agree with all of this... BMW seemed to have added the Runflats as an afterthought and used a marketing game to 'promote' them. Of course the safety issue is true but at a huge detriment to other factors.

The 3-series seems to have been better 'tuned' for them but this may have more to do with the choice of tyre - The Eurofia's are not available on the 5-series...

I'm sure things will improve but I doubt they can ever iron out all the 'issues' of Runflats...

vern

Kieth,sorry,I didn't say that the car was designed arounr the RFT/s.I said the suspension was.I recall reading about it in one of the Auto Magazines.
cheers
vern

Farbton

PS2's are great tires for handling and ride, and wear. Problem is durability. I have gone through 3. One shredded mysteriously on the highway. One ripped out the sidewall after a light bump on the curb (wife driving), and one was a nail so I will let that one pass.

Note Michelin used to promote this as their "Formula 1 tire for passenger cars". After the US Grand Prix fiasco last year they no longer do this. I was at the USGP so I have a personal issue with this as well, but in my mind I wonder if the first two cases were due to "driver error" or Michelin error.

Great tire, but for close to $300 installed for the rears it is tough to justify the durability.

wolverine

The tires, and certainly the sidewall is part of the suspension. You can think of the tire and sidewall as an air filled rubber spring. If you stiffen the tire, either by increasing the air pressure or the sidewall stiffness, then you will have a harsher ride. A stiffer sidewall that deflects less will also give you sharper turn-in response. This is why a larger wheel/tire combo can improve the handling feel.

When going over bumps, if you have a stiff sidewall, you get more compression of the springs and shocks because the sidewall is compressing less. One of the problems with the runflats is their sidewall is so stiff that a lot of the deflection is transferred to the suspension and the driver will feel a harsher ride.

On the other hand, the stiffer sidewall will give sharper turn-in response because the sidewall will not deflect sideways as much when turning the wheel. A softer sidewall tire can give you that 'floating' feeling compared to the runflats - I experienced the same thing with my Michelin A/S tires. However, if you get really top-notch maximum performance tires, such as the Goodyear F1 GS-D3's, or Michelin PS2's, they will give you fantastic turn-in without sacrificing the ride quality.

colejl

I'd agree with that too. Going from the Dunlop DSSTs (Worst tyre on the planet) to the PS2's I haven't noticed a lack of 'turn-in'...

Wiss545

I Drive my car in Saudi Arabia in a hot climate all year long. my Dunlop Run Flat tires makes my ride really stiff.

I red lots of posts about the difference in comfort between the RFT and normal tires but did not really consider that untill couple of weeks back when i took a loan car from the dealer a 520 with non-RRFT. I was amazed with the comfort difference between the 520 and the my 545.

i made a research among the long tire dealers (Micheling/Pirelli and Bridgestone) in order to swicth to normal tire, but the think that is making me think twice is that i dont have a spare tire nor tools, but still i strongly beleive thata shift to traditional tires is a must since most of the rattles coming from the hardness of the ride.

regards