Z4-forum.com

Hi , not very technical and getting a bit confused, so any help/advice would be appreciated.

Bought my 2006 2.5i z4 about 18 months ago, previous owner seems to have put M sport (style 400) alloys on it with 225/45/18 tyres on the front and 255/40/18 tyres on the back.

I'm about to change the tyres later this year and want to go back to the original sizes of 225/40/18 front and 255/35/18 back, also going from run flats to non run flats.

Not knowing much about this, does this seem OK or can anyone see any problems.
Thanks.

No reason at all why not but you might want to consider 245 40 18 on rear to keep comfort & keep arch gap reduced .

Keep it OEM, do not overthink 500 BMW engineers.
225/40 and 255/35 rear.

Panta Rhei wrote: ↑Sun Apr 05, 2020 9:33 am Keep it OEM, do not overthink 500 BMW engineers.
225/40 and 255/35 rear.

Agree keep it original, will be much better without RF aswell!

Panta Rhei wrote: ↑Sun Apr 05, 2020 9:33 am Keep it OEM, do not overthink 500 BMW engineers.
225/40 and 255/35 rear.

So keep with the runflats is your advice

215 is too much strech on a 8" wheel. There is no need really for that width. Sure you can go 205, but why?

Panta Rhei wrote: ↑Sun Apr 05, 2020 9:44 am 215 is too much strech on a 8" wheel. There is no need really for that width. Sure you can go 205, but why?

Where is 215 mentioned

245* 8,5* 235*

Panta Rhei wrote: ↑Sun Apr 05, 2020 9:46 am 245* 8,5* 235*

That supposed to mean something

215 is too much strech on a 8" wheel. There is no need really for that width. Sure you can go 205, but why?

Put 245 instead of 215
Put 8,5 instead of 8
and 235 instead of 205
I made a mistake and referred to your other post where you suggest 215 instead of 225. here you do the same with 245 instead of 255.

Panta Rhei wrote: ↑Sun Apr 05, 2020 9:50 am

215 is too much strech on a 8" wheel. There is no need really for that width. Sure you can go 205, but why?

Put 245 instead of 215
Put 8,5 instead of 8
and 235 instead of 205
I made a mistake and referred to your other post where you suggest 215 instead of 225. here you do the same with 245 instead of 255.

Which other post would that be ?
215 is a option to consider if the offset is aggressive or car lowered & along with 225 is perfectly ok for 8j
Same goes for a 245 40 on a rear , no negative reason why not to & plenty of positives why you should do

viewtopic.php?f=49&t=106179&p=1726098&h ... m#p1726098

I would choose the Riva but don't fit 235 35 tyres to the front , go 225 & if lowered & you do get a slight rub ( which you most likely won't ) then 215 35 will cure it , rear 255 35 19 is the tyre size i would go for , its a 9j width so no wider needed
Idej jedi & many others run the same sets with those offsets

So, as I sad I have to disagree. If you can't fit a wheel with a given offset - do not do it. Going for a narrower tyre is not a solution in my eyes.
Secondly, you have 0 side rim protection. Tyre is trapeze shape from behind. Just my opinion.
If something cannot fit with a proper sizes - do not try to fit it at all costs.

I’ve got 215-45-18 on the front with 18x8 due to 20 offset.

Certainly not an extreme stretch and the car now drives, corners and soaks up bumps much better than it did with the previous 19s I had fitted

Panta Rhei wrote: ↑Sun Apr 05, 2020 10:01 am viewtopic.php?f=49&t=106179&p=1726098&h ... m#p1726098

I would choose the Riva but don't fit 235 35 tyres to the front , go 225 & if lowered & you do get a slight rub ( which you most likely won't ) then 215 35 will cure it , rear 255 35 19 is the tyre size i would go for , its a 9j width so no wider needed
Idej jedi & many others run the same sets with those offsets

So, as I sad I have to disagree. If you can't fit a wheel with a given offset - do not do it. Going for a narrower tyre is not a solution in my eyes.
Secondly, you have 0 side rim protection. Tyre is trapeze shape from behind. Just my opinion.
If something cannot fit with a proper sizes - do not try to fit it at all costs.

Fair dos , you are entitled to your opinion but i think you will find that a 215 35 19 tyre will fit a 8j rim without any issue ( as in the set of Riva i'm discussing above) it will not be significantly stretched or as you put it "trapeze" & is a viable option for someone with a lowered e85/e86 who doesn't want to rub the liner .
Also to put the advice i offered in context its worth reading the whole thread

Sure thing, just a exchange of views