Help Tire Size Change 2008 Z4si

KLEETIS · 01-05-2021, 10:57 AM

I'm looking to change tire size on my 08 Z4si factory stock wheels it has the Sport package 18" wheels I beleive the factory lowers the suspension on this model.
1- Does anybody know the width in inches Front 18x8" is correct?
2-Rear 18x9" is correct?
Important for me without changing or adjusting anything front or rear will I run into any problems?
1-I want to change the front from 225/40R 18 to 235/40R 18 is there any rubbing concerns?
2-I want to change the rear from 255/35R 18 to 265/35R 18 also is the there any rubbing concerns? and is the rear wheel at least 9" wide tire company wants this for a 265/35R 18 tire?
Using a tire caculator there is not much difference is height width. Has anyone done this on the same car? Thank You for you time!
One last thing I was going to go to regular tires and carry a plug kit.
Anyone more happy with regular tires over run flats?
I know it sounds simple and they should fit just want to be sure. This is my second BMW first was a 98 Z3M silver should have kept it!

KLEETIS · 03-02-2021, 09:19 AM

About ready to delete this. Somebody must know if they will rub or not?:

Steeler · 03-02-2021, 10:19 AM

Quote:

Originally Posted by KLEETIS

About ready to delete this. Somebody must know if they will rub or not?:

I ran 265/35/18 on et 35 18x9.5 and 235/40/18 on et 35 18x8.5 with slight rubbing on the rears.
Lowered 1" all around.

Run flats ride harsh. No concerns with conventional tires. Carry a plug kit if you drive where you may pick up a puncture.

Your results may vary.

Roadroach · 04-01-2021, 10:16 AM

The 18" rims on the sport package are 18x8 in the front and 18x8.5 in the rear.

bmwstylewheels.com is a good resource for specs on all bmw wheels (they list sizes/offsets and weights for nearly all bmw wheels).

My understanding is that 255 is about as wide as you can go on the stock 8.5" rear rim.

01-05-2021, 10:57 AM	#1
KLEETIS Registered 0 Rep 3 Posts Drives: 2008 BMW Z4si Sport Package Join Date: Jan 2021 Location: Hudson Valley NY iTrader: (0)	Help Tire Size Change 2008 Z4si I'm looking to change tire size on my 08 Z4si factory stock wheels it has the Sport package 18" wheels I beleive the factory lowers the suspension on this model. 1- Does anybody know the width in inches Front 18x8" is correct? 2-Rear 18x9" is correct? Important for me without changing or adjusting anything front or rear will I run into any problems? 1-I want to change the front from 225/40R 18 to 235/40R 18 is there any rubbing concerns? 2-I want to change the rear from 255/35R 18 to 265/35R 18 also is the there any rubbing concerns? and is the rear wheel at least 9" wide tire company wants this for a 265/35R 18 tire? Using a tire caculator there is not much difference is height width. Has anyone done this on the same car? Thank You for you time! One last thing I was going to go to regular tires and carry a plug kit. Anyone more happy with regular tires over run flats? I know it sounds simple and they should fit just want to be sure. This is my second BMW first was a 98 Z3M silver should have kept it! Last edited by KLEETIS; 01-06-2021 at 06:45 AM..
	Appreciate 0 Tweet Quote

03-02-2021, 09:19 AM	#2
KLEETIS Registered 0 Rep 3 Posts Drives: 2008 BMW Z4si Sport Package Join Date: Jan 2021 Location: Hudson Valley NY iTrader: (0)	About ready to delete this. Somebody must know if they will rub or not?:
	Appreciate 0 Quote

04-01-2021, 10:16 AM	#4
Roadroach First Lieutenant 165 Rep 305 Posts Drives: 2006 Z4 3.0si coupe w/stick Join Date: Jan 2015 Location: Austin, Texas iTrader: (0)	The 18" rims on the sport package are 18x8 in the front and 18x8.5 in the rear. bmwstylewheels.com is a good resource for specs on all bmw wheels (they list sizes/offsets and weights for nearly all bmw wheels). My understanding is that 255 is about as wide as you can go on the stock 8.5" rear rim. __________________ 2006 Z4 coupe - with HOMELINK! 1966 Mustang GT fastback (too many mods to list) 2015 335i GT 2014 981 Cayman S manual
	Appreciate 0 Quote