Run Flats or Not?

[sageriders]

I own a 2006 E53 4.4Sport, purchased new from a dealer. I believe the standard wheel/tire combo on the 3.0 and 4.4 was a 17", but the Sport was un upgrade to 18s. My spare is on a 17" wheel. My tires are 255/55x18 all the way around, and I run the OE Michelins. Never had any problem with them; good mileage, quiet, etc. My guess is that a previous owner converted your car to run flats, as I do not believe they were available in 2006.

The TP monitor is an odd kind of thing - that reads the wheel revolutions, and when it senses that one wheel is running slower because of reduced pressure, it sends the signal to the dash display. Mine occasionally gives false readings, especially when there is a significant weather or temp change - since tire press is affected by air temp. As and example, if one side of the car is in bright sun and the other in shade, I can get a low pressure warning signal. Usually it's only the temp difference that causes it.

[Salty_Dog]

Originally Posted by sageriders

I own a 2006 E53 4.4Sport, purchased new from a dealer. I believe the standard wheel/tire combo on the 3.0 and 4.4 was a 17", but the Sport was un upgrade to 18s. My spare is on a 17" wheel. My tires are 255/55x18 all the way around, and I run the OE Michelins. Never had any problem with them; good mileage, quiet, etc. My guess is that a previous owner converted your car to run flats, as I do not believe they were available in 2006.

2006 BMW X5 3.0d in AU had 20" 168 Rims and tyres, when you got the Sports/Premium package.
275's fronts and 315's in the rear, as expressed below

Originally Posted by sageriders

The TP monitor is an odd kind of thing - that reads the wheel revolutions, and when it senses that one wheel is running slower because of reduced pressure,

I think you mean, running faster

[X53Jay4.8is]

Originally Posted by upallnight

I would be more concern with the wear and tear on the differential and the transfer case from running tires that doesn't have the same circumference as one another.

Say What? Spare overall is the same in height to the road tires

[upallnight]

Originally Posted by X53Jay4.8is

Say What? Spare overall is the same in height to the road tires

If you read the OP original post, he is thinking of getting rid of the run flat tires and going with tires that doesn't have such a low profile. If he sticks with the 20" rims that he has right now, going to tires with a higher profile and a more compliant sidewall will change the circumference of the tire compare with what he has in the trunk.

He will need to also replace the spare tire so that the circumference matches his new road tires.

[Salty_Dog]

Originally Posted by X53Jay4.8is

Say What? Spare overall is the same in height to the road tires

Obviously thinks BMW don't pay attention to small details, like spare wheels

[Salty_Dog]

Originally Posted by upallnight

If you read the OP original post, he is thinking of getting rid of the run flat tires and going with tires that doesn't have such a low profile. If he sticks with the 20" rims that he has right now, going to tires with a higher profile and a more compliant sidewall will change the circumference of the tire compare with what he has in the trunk.

He will need to also replace the spare tire so that the circumference matches his new road tires.

Oh, i wasn't gong to change the profile, just the side wall flex of a Non Run Flat.
But i see your point.

Have some of you gone a bigger profile tyre on the 20" Rim for ride/comfort reasons?

Yes, in that case, i would have an issue with the spare wheel
Also Speedo accuracy.

[X53Jay4.8is]

Originally Posted by upallnight

If you read the OP original post, he is thinking of getting rid of the run flat tires and going with tires that doesn't have such a low profile. If he sticks with the 20" rims that he has right now, going to tires with a higher profile and a more compliant sidewall will change the circumference of the tire compare with what he has in the trunk.

He will need to also replace the spare tire so that the circumference matches his new road tires.

Looked at first post and he is running 20s and yes the spare is a 17 but the combination of 17 plus tire diameter ends up being the same as the 20 inch rim and smaller side wall profile of the 17 inch tire. Overall they are the same diameter. Just like on my 4.6is. I think he just wants to know if he can ditch the run-flats in favor for some regular tires since he has a spare already.

[bcredliner]

I see no reason for run flats when you have a spare. More expensive and in my experience when run flats go flat you're not going very far before they come apart.

There are non run flat stock size choices out there that deliver a much softer ride. I don't think you need to go to taller tires. Based on where you want to go I would suggest stock size tires with the most flexible sidewalls and play with inflation a bit.

[Salty_Dog]

That is what i was hoping for bcredliner

As currently, on a very well made hwy, its a brilliant ride, but those other roads with bitumen changes, its like driving over bricks.