Run flat tire pressure
Thread Starter
Senior Members
Joined: May 2004
Posts: 1,809
Likes: 0
From: Not here
When the dealer inflates my run flats, they put in the same air pressure in all tires. In the manual it indicates that different tire pressures for the front and rear are to be used for my tires (Bridgestone Potenzas).
I'll ask the dealer next time I'm in but I was wondering if anyone has addressed this issue?
I'll ask the dealer next time I'm in but I was wondering if anyone has addressed this issue?
Senior Members
Joined: Apr 2004
Posts: 700
Likes: 0
From: columbus ohio US
By the way, does anyone know how the low air pressure signal is sent from the tire to the display??
I noticed before I dropped off my car at the end of ED that one of the valve stem caps was missing. Does the signal go through that? I know this has got to be more simple than I'm making it out to be.
I noticed before I dropped off my car at the end of ED that one of the valve stem caps was missing. Does the signal go through that? I know this has got to be more simple than I'm making it out to be.
Senior Members
Joined: Nov 2003
Posts: 723
Likes: 0
From: Norway
RPA is based on the rotation of the wheels, and any eventual differentiation in the rotational speed between one wheel and the other three. Thus the RPA system isn't extremely accurate, and will most likely fail to report pressure losses on two or more tyres. However it's convenient in case of a tyre breakdown or sudden pressure loss on one wheel.
The valves don't contain any transmitters.
-paasan
The valves don't contain any transmitters.
-paasan
Contributors
Joined: Feb 2006
Posts: 228
Likes: 0
From: Colorado USA
My Ride: 535ixT � On Order: 2010 E61, Ordered 1/05, Est. Birth 3/09, Est. Delivery 4/09, Carbon Black, Cream Beige Dakota Leather, Steptronic, M-Sport Pkg., Type 135 18
Model Year: 2010
Initially I had the factory recommended 30F/36R in my 530xiT's tires.
I was very unhappy with the handling - the car felt as if it had wet spaghetti for anti-roll bars. I had been looking all over for aftermarket stabilizer bars as the X-drive cars are not available with Active Roll Stabilization (ARS).
Then my dealer put 39 psi all around before our trip to from the East Coast to Colorado. That changed the car's demeanor from a near-Detroit wallow to a much more drivable car with good turn-in characteristics and much flatter cornering - now its not an M-Car - but it does drive like a BMW!
This change in relative pressure (front to rear) reduces understeer - that may be of concern to some - but I think that the X-drive and DSC should keep one out of oversteer problems if one keep the pace below 7/10.
I was very unhappy with the handling - the car felt as if it had wet spaghetti for anti-roll bars. I had been looking all over for aftermarket stabilizer bars as the X-drive cars are not available with Active Roll Stabilization (ARS).
Then my dealer put 39 psi all around before our trip to from the East Coast to Colorado. That changed the car's demeanor from a near-Detroit wallow to a much more drivable car with good turn-in characteristics and much flatter cornering - now its not an M-Car - but it does drive like a BMW!
This change in relative pressure (front to rear) reduces understeer - that may be of concern to some - but I think that the X-drive and DSC should keep one out of oversteer problems if one keep the pace below 7/10.
Senior Members
Joined: Nov 2005
Posts: 1,113
Likes: 0
From: Albany, NY
My Ride: '04 545iS 6 spd, bought new via eBay, 11/05; Blk/Gry, Cold, L7, PDC, BMW Rear seatcover for pets.
First "Bumwa" was a new 1971 2002. High performance 5s since 1987. Beamer motorcycles too, currently on an 07 BMW K1200 GT; also a Moto Guzzi 1000 SP III.
Well Jimbo, since you don't say which model or tire size you are running, it's tough to speculate. I'd go by the door-jamb decal, it is most specific to the car (manuals are printed too far in advance).
That being said, the very complex symbol pattern on my decal (for 545iSport with 18" runflats) does NOT differentiate between front and rear (though it does for other tire applications). Go figure.
All I know is that when mine was delivered it rode like a buckboard and was jarring everything loose. A couple weeks later I mounted traditional snows and everything went to being as expected in a high performance luxury car. This spring, when I switched back, I instructed the dealer to set the RFTs to MINIMUM RECOMMENDED pressure, and the difference was, well, palpable. I never checked to see what the setting was, but assume it was the unladen (no passengers or baggage) setting and it was much more comfortable.
Last month, I got a new set of Dunlops under warranty (@6000 miles), and they are more comfortable, and seem to be a big improvement over the old ones. Can't speculate on comfort of Bridgstones, but others here claim they are harsh.
Bottom line is get them set, IN AXEL PAIRS, (how electronic measurements are taken) to the door jamb decal for your model, and go from there, according to your usual load in the car.
Cheers,
Ray Hull
That being said, the very complex symbol pattern on my decal (for 545iSport with 18" runflats) does NOT differentiate between front and rear (though it does for other tire applications). Go figure.
All I know is that when mine was delivered it rode like a buckboard and was jarring everything loose. A couple weeks later I mounted traditional snows and everything went to being as expected in a high performance luxury car. This spring, when I switched back, I instructed the dealer to set the RFTs to MINIMUM RECOMMENDED pressure, and the difference was, well, palpable. I never checked to see what the setting was, but assume it was the unladen (no passengers or baggage) setting and it was much more comfortable.
Last month, I got a new set of Dunlops under warranty (@6000 miles), and they are more comfortable, and seem to be a big improvement over the old ones. Can't speculate on comfort of Bridgstones, but others here claim they are harsh.
Bottom line is get them set, IN AXEL PAIRS, (how electronic measurements are taken) to the door jamb decal for your model, and go from there, according to your usual load in the car.
Cheers,
Ray Hull
Contributors
Joined: Sep 2006
Posts: 21,274
Likes: 0
From: Hong Kong
My Ride: Mini Cooper
Originally Posted by Ray Hull' post='340262' date='Sep 30 2006, 09:25 PM
Well Jimbo, since you don't say which model or tire size you are running, it's tough to speculate. I'd go by the door-jamb decal, it is most specific to the car (manuals are printed too far in advance).
That being said, the very complex symbol pattern on my decal (for 545iSport with 18" runflats) does NOT differentiate between front and rear (though it does for other tire applications). Go figure.
All I know is that when mine was delivered it rode like a buckboard and was jarring everything loose. A couple weeks later I mounted traditional snows and everything went to being as expected in a high performance luxury car. This spring, when I switched back, I instructed the dealer to set the RFTs to MINIMUM RECOMMENDED pressure, and the difference was, well, palpable. I never checked to see what the setting was, but assume it was the unladen (no passengers or baggage) setting and it was much more comfortable.
Last month, I got a new set of Dunlops under warranty (@6000 miles), and they are more comfortable, and seem to be a big improvement over the old ones. Can't speculate on comfort of Bridgstones, but others here claim they are harsh.
Bottom line is get them set, IN AXEL PAIRS, (how electronic measurements are taken) to the door jamb decal for your model, and go from there, according to your usual load in the car.
Cheers,
Ray Hull
That being said, the very complex symbol pattern on my decal (for 545iSport with 18" runflats) does NOT differentiate between front and rear (though it does for other tire applications). Go figure.
All I know is that when mine was delivered it rode like a buckboard and was jarring everything loose. A couple weeks later I mounted traditional snows and everything went to being as expected in a high performance luxury car. This spring, when I switched back, I instructed the dealer to set the RFTs to MINIMUM RECOMMENDED pressure, and the difference was, well, palpable. I never checked to see what the setting was, but assume it was the unladen (no passengers or baggage) setting and it was much more comfortable.
Last month, I got a new set of Dunlops under warranty (@6000 miles), and they are more comfortable, and seem to be a big improvement over the old ones. Can't speculate on comfort of Bridgstones, but others here claim they are harsh.
Bottom line is get them set, IN AXEL PAIRS, (how electronic measurements are taken) to the door jamb decal for your model, and go from there, according to your usual load in the car.
Cheers,
Ray Hull
I like to ask can you take a pic of the door-jamb decal?I dont have 1 on my car, My tyres are 19" 245/35 front and back and they are not RFT.
So what tyre psi do I put on my fronts and back?
people say 38 front and 42 back is this right for my?
thanks
Contributors
Joined: Jul 2006
Posts: 1,180
Likes: 0
From: Oxfordshire, UK
My Ride: E61 535d Apr 05. UK spec + Media Pack, Luxury Pack & Visibility Pack
With 19" rims I doubt you'd find them on the decal anyway. It only has standard (16, 17 and 18") rims on it!
In my view, your pressures sound a little low with such low profile tyres, especially the rears, but I think it comes down to personal preference (mine are closer to Ray's than Hopco's - at least with RFT). I'd try it with 38 and 44.
I'd take a picture of the sticker, but mine is an E61...
In my view, your pressures sound a little low with such low profile tyres, especially the rears, but I think it comes down to personal preference (mine are closer to Ray's than Hopco's - at least with RFT). I'd try it with 38 and 44.
I'd take a picture of the sticker, but mine is an E61...
