Run Flat Tires

vincegalluccio · Mar 27, 2006

About to buy a 2006 650 convert. The sport package has the low profile run flat tires on 19 inch rims as the standard offering. The lows have always given me concern for road damage and sidewall vulnerability. It is especially makes me wonder since the 6 carries no spare. Any one have any experience with this one??
The new baby will live in Southwest Florida and replace a 500SL.

Big Daddy · Mar 27, 2006

Not too many BMW's come with spares anymore, my 98 M rodster has not spare! I hate run flats, they have greatly reduced performance. Buy good tires, get roadside assistance and carry canned air, that's what I do. I have owned a spareless roadster since 98 and have never (knock on wood) had a flat!

frolf · Mar 27, 2006

that is good advice. run flats are loud, though tech has got so much better since they first came out years ago.

epj3 · Mar 27, 2006

I'm not sure if the 6 is the same as the 3, but the new 3's suspension was designed to work with run flat tires only, so I'm not sure if handling would change becuase of it.

Big Daddy · Mar 27, 2006

How do you design a suspension to "work" with run flats? I know many e90 owners who swear the car handles better after replacing the factory run flats. All test data I have seen indicates that the run flats do not perform as well as non run flats. But hey all I know is track junkies!

epj3 · Mar 28, 2006

Big Daddy said:

I'm not sure, you better email BMW because it was their words. I tend not to argue with german engineers about cars. I don't recall saying they will handle worse, I was just saying to do the research first since BMW claims the suspension was designed around runflats. I think my post was more than justified, since it is something he should probably research, unless you support giving advice with a little twist of ignorance. Couldn't find the original article from BMW, but here is from the media

"...when, as is the case of the E90 3 Series, the suspension has been tuned to accommodate the stiffer sidewalls of a run flat tyre, the overall ride quality isnt noticeably inferior."

Big Daddy · Mar 28, 2006

epj3 said:

Ok ease up, I just mentioned some facts, run flats do not perform as well as non-run flats! You than rebuke me with "better email BMW because it was their words" yet you cannot quote the source. Why do you suggest I "support giving advice with a little twist of ignorance"? I can back my position up with fact, can you?

Let me help you Eric, here is a quote defending your psoition on suspension tuning for run flats, "The automakers have also started tuning their suspensions specifically for run-flats. One tweak is relaxing the “durometer,” or stiffness of the suspension bushings, to help cushion impacts that would better absorbed by a conventional tire." (from "The Skinny on Run Flats", Mobil Oil) Notice that therein is some of your lost performance, they are asking the suspension bushings to do some of the old job formally done by your tires.

Also from Mobil Oils web site regarding performance. "All three strategies have their pros and cons. Self-sealing tires don’t require special wheels or reinforced sidewalls, but the lining isn’t foolproof and, if it fails, the car must stop in a safe manner. The tire-within-a-tire lets engineers specify exactly the tire profile they want while assuring that you can still drive after the blowout, but requires a special wheel rim. If you had a set of such tires, those 20-inch chrome wire wheels you have been shopping for are out. The special rim also adds “un-sprung weight,” or weight not supported by the suspension. Gains in un-sprung weight are the worst kind from a vehicle dynamics standpoint, disproportionately affecting the handling and ride."

And Eric, really qouting the media, which media and how would they know??? [:p]

deutsch100 · Mar 28, 2006

As someone who has run flat tires on my E90...I can say that I honestly feel that they handle as well as "regular tires", but I feel the ride quality is inferior.

I would prefer to have my regular beloved Continentals and a can of air..just like Big Daddy!!

vincegalluccio · Mar 28, 2006

Big Daddy said:

Thanks,
I feel the same way. On a factory order I am told by the dealer that you must opt out of the sport package and accept the standard 18 inch rims. So I think I will do that and make a decision on the aaptive steering and the HUD. Again thanks for the thoughts.

Big Daddy · Mar 28, 2006

I am sure that over time they have gotten better and will continue to improve, but it is something that the car has to come equipped with. I hear to "upgrade" to run flats is $$$$!

epj3 · Mar 28, 2006

Big Daddy said:

I still think you missed the point of my post... I was suggesting they do research to make sure there won't be any issues going with non-run flat tires (like performance or driveability loss.) I never said run flats perform as well!! I sure as hell wouldn't opt for run-flats! I see runflats as being designed for women and men who are too wussy to change a spare or too cheap to get some kind of road-side assistance program, and since you can't find ZR performance rated run flats, it says something else.

Big Daddy · Mar 28, 2006

Okey Dokey Eric, sorry I missed your point. I am by no means a run flat expert and I agree, people should research before buying...now I am going to charge my battery in the roadster as she is door nail dead [xx(]

Section_8 · Mar 28, 2006

epj3 said:

I hear that.

I'm semi-shopping E90's right now, I'm sooo close to putting this E46 to the side as 'garage queen' and SC'ing it out for the track and getting another DD.. Guess I need to tally in wheels and tires into my E90 purchase.. I didn't realize when I got my current car that I was lucky to have a full size spare (or a wheelwell in the trunk for that matter..)

epj3 · Mar 28, 2006

Big Daddy said:

yea batteries suck, they are way too expensive.

deutsch100 · Mar 28, 2006

Dan, just keep it on a BMW battery maintenance charger. We keep the Z8 on one, especially when we are back home in Germany/Sweden. The Z8 is known to have battery issues, and with our gel maintenace charger..we have NEVER had an issue. We picked it up at our local dealership. Try it.

-Adam

Big Daddy · Mar 28, 2006

deutsch100 said:

Thanks Adam, I had her on a .5 Amp motorcycle trickle charger most of the winter. Wondered if my charger went bad as the current battery is not even three years old (6 yr Warranty Delco Pro Series) so I bought another high end charger, trickle at .5 amp, slow charge at 1.5 amps and a full fast 6 amp charge mode! Took the battery in to an authorized Delco dealer after being on the new charger over night. Load test shows 0 cranking amp [ohcrap]

! They replaced it under warranty and now I have a new charger, six year warranty on my battery and a roadster that starts! [bmwdance]

deutsch100 · Mar 28, 2006

Glad to hear you got a new charger Dan and most importantly...an ///M that starts!

Militant-Grunt · Mar 28, 2006

Big Daddy said:

I would have a can of fix a flat in there just in case.

MrElussive · Mar 28, 2006

Big Daddy said:

I agree, I think BMW's statement is kind of bogus. I think at most, BMW just did their best to give the new E90 a smooth ride from the run-flat tires.

Run-flats typically do not handle and ride as well as regular tires, and they wear down significantly faster. Not to mention that as some punctures on regular tires require you to purchase a whole new tire, run-flats follow this same system as well.

That being said, I think they are still worth it. Some cars cannot accomodate a spair, and it is worlds easier to just drive your car home or straight to a gas station when you get a flat tire, as opposed to changing the tire yourself (especially if it's cold and/or dark out!).

Big Daddy · Mar 28, 2006

Militant-Grunt said:

Sorry, I meant 2 cans of "fix-a-flat" and I have an air compressor as well.

Run Flat Tires

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