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Technical Topics Wheels and Tires Opting for 18 inch A/S RFT or non-RFT?

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      08-06-2019, 10:05 AM   #1
ThatKrazyPolak
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Hey you crazy kids,

Have a question more aimed towards those that already have the 330/M340. Thinking of placing an order for M340xi soon but don't know if I should opt for the 18 inch run flats or non runflats. I currently have 225/40 tires on my two series and hate them, had to buy 2 tire insurance policies as I had more then 5 tire replacements over 4 years.

Obviously, I want to prevent this as much as possible, and I've noticed that the Performance tires and non-RFT A/S have 255 / 40 in the rear.I also see that the RFT's run 225 / 45 both front and back. Any recommendations on whether I should opt for the RFT's or non-RFT's and whether the extra tire width makes a difference? I live in Jersey and roads are bad in the winter. I know tire issues are not preventable but I want to try to not have to buy the tire insurance again. The dealer told me that all the cars come equipped with run flats and they tried to sell me on the "extra 100 miles in the event of failure" nonsense that we hear a million times. I'd appreciate any insight here.
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      08-07-2019, 07:39 AM   #2
dirtdog
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Hello,

I'm going with non run flats. I also live in NJ. I had no issues with non run flats on my 2 series. The run flats on my 3 series have been nothing but trouble. Thx.
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      08-07-2019, 08:07 AM   #3
sanch8
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I don't know if ride quality is a concern, I have 19" RFTs A/S 225s all around on my Msport 330ix with adaptive suspension and still hate the ride quality. At the same time I have driven loaners with 18" RFTs with standard suspension and the ride quality is significantly better. So at 18" ride quality for RFT vs, non RFT may not matter much but it does matter if you go 1 size up. I plan on switching to 19"225X4 non RFTs the first chance i get.

Wrt. to having a wider tire in the back, there are a few pros and cons, the biggest pro being the car looks visually more pleasing with the flatter tire in the back imo. It may also help put down the power faster on a RWD and also nudges the car towards understeer, which is a con. However, having the same tire all-around, especially on an xdrive version, will give you a more balanced driving feel, which should equate to more confidence in cornering. You will also be able to rotate your tires, prolonging tread life.

If you plan on acquiring another set of tires for winter then my suggestion would be to go for perf. non RFTs in 19" and acquire another 18" 225X4 for the winter. If going to stick with only one set then go for 19" 225X4 non-RFT.
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      08-07-2019, 08:20 AM   #4
phillyd2
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I did 18-non runflats because I'll never do runflats again.

I'm over 2K miles and have had no issues or drama.
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      08-14-2019, 10:50 AM   #5
ThatKrazyPolak
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I don't know if this matters, but from looking at the tire does it seem that the non-RFT are larger then the RFT's? Whenever I go to a dealership all I see are RFT's can't make a comparison. I just want to ensure if I hit a pothole there's a chance I'm going to be more protected than with a RFT.
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      08-14-2019, 11:06 AM   #6
sanch8
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You can compare tire specs in detail on tirerack.com. There's no magin bullet, if you hit a pot hole hard enough with either tire, you are going to end up damaging - tire>rim>suspension. With a standard tire, the sidewall is going to compress faster to cushion the blow to the rest of the components vs. a run flat tire where the jolt is going to travel faster up the chain with rim and suspension taking more of the beating.
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      08-29-2019, 02:57 PM   #7
dtristao
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Quote:
Originally Posted by sanch8 View Post
I don't know if ride quality is a concern, I have 19" RFTs A/S 225s all around on my Msport 330ix with adaptive suspension and still hate the ride quality. At the same time I have driven loaners with 18" RFTs with standard suspension and the ride quality is significantly better. So at 18" ride quality for RFT vs, non RFT may not matter much but it does matter if you go 1 size up. I plan on switching to 19"225X4 non RFTs the first chance i get.
When you say ride quality, means handling / confort ?
I'm planning to get G21 with 19' along with adaptive suspension, but afraid that will still be too stiff as it will be my everyday car, can you share your experience?

PS: these 19' JLL 793 are RFT only
Thanks
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