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[dr.bmw]

I want to go with a 225/45/17 Michelin PS2 ZP runflats all around on my 125i. Should be no problem with the rears, but I'm not so sure about the fronts, the rim is 7J as far as I could ascertain and i can not find a confirmation anywhere as to the widest tyre one can fit on a rim that size.
Also has anyone tried the setup on their car and does it make any difference to the understeer issues?
Cheers.

[Macca916]

An online tyre/wheel calculator lists a 225/45x17 as needing a 7.5" rim as min width. 215/45x17 via same calc drops down to 7" min width. This is a generic calc and some tyre manufactures may have different recommended rim widths. You can get a huge variance in tyre widths from different manufactures and I've seen 225s on an 8" rim that looked too stretched. The tyre will fit but may lead to too much flex in the sidewalls . Note this is just the info I've found from years of car nerdship, I'm sure an expert will be along soon to answer with more accuracy.

[Artmasterx]

I run 225/45 r17 General Exclaim UHPs on my 128i (7" front, 7.5" rear). They fit fine, but they are also NOT runflats. The stiffer sidewalls of the runflats may make it more difficult to mount on a 7" rim. My tire lists the acceptable rim widths as 7-8.5" on Tirerack.

The non-runflat PS2 also lists a 7" rim width as acceptable. Unfortunately, the ZP PS2 has nothing for acceptable rim width on Tirerack.

[Fireflyer239]

As an example, the popular CSL rep package many here are running typically uses a 225/40 up front, on the 18x8.5 wheel (with 255/35's out back on 9.5's). Interesting to note that at the same time, the typical Breyton GTS-R setup uses a 255/35 rear tire on the same size 18x8.5 wheel! (same as the CSL fronts). Tire rack lists the 8.5 wheel as within the proper fitment range for both tires. (225/40/18 proper rim width is 7.5" - 9", while 255/35/18 proper rim width is 8.5" - 10") In any case, a 225 should not seem too stretched (at all!) on an 8" wheel but then again, tires run different from one another, as you say. When you're looking at any tire detail on TR's site, just click on "specs" and all this info is there. Personally, I am considering running the CSL reps in square configuration - 8.5's all around with 225/40/18's. Considering Breytons still (for the lightness), but the kids are saying something about needing to eat...or something, lol.

[SV Concepts II]

It will fit fine. 225 PS2 ZP's are rated for 7-8.5'' wheels.

[davidk]

I have been thinking about putting 225/45x17 on the front of my 128 M-sport as well. My main concern is that since the wheel is 1/2" narrower than the rear the tire will look pinched, or like I am trying to put too much tire on a small wheel, even though most specs I have seen indicate a 7" wheel will work for this size tire. Artmasterx, how's it look? Can you post a picture of it? Any difference with the handling?

[Artmasterx]

Check out this thread for more details.
http://www.1addicts.com/forums/showthread.php?t=267999

[davidk]

Thanks, Artmasterx - that was exactly the information I have been looking for.