[crank73]

Hi all, how are you guys determining whether a tire and rim combo will work or not? Is there a good website that helps determine that?

I have the stock 397 style 18 inch wheels on a square setup for my 428i. I see from the sticky that they are 18/8 with a 34 ET.

I found some rims for a staggered setup and they are
Front 19/8.5 with a 35 ET
Rear 19/9.5 with a 40 ET

I'm trying to figure out if I can put the following tire on them and have it work with the 428i
Front 225/40/19
Rear 255/35/19

Thanks

[floydarogers]

Pretty much everyone uses tirerack.com and it's tech articles to understand all the numbers. It's all numbers; you have to draw your own conclusion after measuring your current fitment and comparing to what the numbers will be with a different set of rims and tires.

[alohasurftoad]

Originally Posted by crank73

Hi all, how are you guys determining whether a tire and rim combo will work or not? Is there a good website that helps determine that? I have the stock 397 style 18 inch wheels on a square setup for my 428i. I see from the sticky that they are 18/8 with a 34 ET. I found some rims for a staggered setup and they are Front 19/8.5 with a 35 ET Rear 19/9.5 with a 40 ET. I'm trying to figure out if I can put the following tire on them and have it work with the 428i. Front 225/40/19 Rear 255/35/19. Thanks

the wheel size and offset you're inquiring about is a common aftermarket fitment for F3x's. 225 is a 20mm stretch on the front and 255 is a 10mm stretch on the rear. 235/40/19F, 265/35/19R is a better fit on the 8.5"/9.5" rim widths (10mm stretch front/perfect rear) and fill out the fenderwell better. 225/255 will work if that's what you prefer, though...

[Uber Commuter]

Read tire rack articles for the understanding; then use this site to test measurements:

http://www.willtheyfit.com/

[crank73]

Alohasurftoad, when you say 20 mm stretch and 10mm stretch, do you mean that the outside edge of the tire of the new setup would be at the same location as if I would put a 20 mm spacer in the front and 10 mm spacer in the rear on my current setup? I'm not opposed to the other size tire you mention. Trying to get a flush finish with the outside edge and the wheel well. I won't be lowering this car ever as it's my everyday driver and the winters here would not allow for it.

[alohasurftoad]

Originally Posted by crank73

Alohasurftoad, when you say 20 mm stretch and 10mm stretch, do you mean that the outside edge of the tire of the new setup would be at the same location as if I would put a 20 mm spacer in the front and 10 mm spacer in the rear on my current setup? I'm not opposed to the other size tire you mention. Trying to get a flush finish with the outside edge and the wheel well. I won't be lowering this car ever as it's my everyday driver and the winters here would not allow for it.

stretch or bulge refers to the tire width to rim width match. if the tire is narrower than the rim width the tire beads have to be stretched to the rim seats. if the the tire is wider than the rim, the tire beads have to be squeezed to the rim seat causing the sidewall to "bulge". 10mm bulges or stretches are almost imperceptible. especially if you're not looking for it.

example: 245 is perfect(no stretch or bulge) on 8.5" wide. a 225 width tire is 20mm narrower than the 245, thus a 20mm stretch. if you put a 255 wide tire on 8.5" it is 10mm wider than the 245 thus it would be a 10mm "bulge", albeit very slight.

if you run 19x8.5 et35 with 225/40/19 tire up front the rim edge will be flush however the upper shoulder of the tire may be tucked due to the stretch. a spacer maybe used to push the shoulder of the tire to flush position. different size tires may also be used to put the tire shoulder at flush without a spacer.

combinations of rim width, tire size, offset, lowering and in some cases additional negative camber, are used to achieve desired look/stance.

sorry if this is confusing. if you are not going to lower it, again i recommend 235/40/19 front, 265/35/19 rear

[crank73]

I just wanted to thank you for taking the time to explain all that. I've been referring to your posts quite often. thanks again.