Tires setup on 19"

N

Niko

New member
Hi everyone!
I'm new and it's my 1st topic so if there is already a similar subject, I have to apology :)

The case:
The car is E86 3.0si
I'm going to change my wheels and put new tires on them.
I've chose BMW 163 CSL style (19" 8.5 and 9.5).
ET of the rims are: 44 front and 27 rear.
I'm thinking to put some thicker and wider tires than they were from factory.

Question:
Will they fit with 235/40 R19" front and 265/35 R19" back?
I've got B12 Pro-kit so: 30mm lover front and 20mm rear suspension.
Does enyone has got similar spec?
Why does M cars has got thicker tires?
I do some maths below.

Maths:
Right, so obviously OEM spec for NON M cars is:
225/40 R18 diameter: 637.2mm
255/35 R18 diameter: 635.7mm
so the best replacement for 19" should be:
225/35 R19 diameter: 640.1mm (almost identical)
255/30 R19 diameter: 635.6mm (almost identical)
hovever...
for Z4 M cars OEM tires spec is:
225x45 R18 diameter: 659.7mm (+22.5mm)
255/40 R18 diameter: 661.2mm (+25.6mm)
so the best replacement with 19" should be:
225/40 R19 diameter: 662.6mm (almost identical)
255/35 R19 diameter: 668.1mm (almost identical)

so what about:
235/40 R19 diameter: 670.6mm (+10.9mm)
265/35 R19 diameter: 668.1mm (+6.9mm)
They will be thicker only 5.5mm front and 3.5mm back than the OEM spec of Z4M and 16.7mm/16.2mm thicker than the NON M spec.

Arguments:
Because OEM spec was on 18" Run Flat tires I only consider NON Run Flat in 19" thinner profile setup.
So for looking wider and more thicker tire (for comfort reason and better grip) I came up with those 235/40 R19 and 265/35 R19.

What do you think?
 
:cry: couldn't read all that to the end :( my mind went all fudgey :dizzy:
gen CSLs on a a Si isn't impossible , a forum member ( France iirc ) has them on his " but " that's not to say he hasn't had issues gotten over with geo tweaks or dropping tyre specs .
As for your 265 35 19 proposed rubber :cry: :cry: i really wouldn't think that would work unless you fit springs off a X5 :P
 
Hi and welcome to the forum from a fellow Coupe owner. :thumbsup:

Don't forget we like to see photos of new members' cars on here!

I've got 19" CSLs (Replicas) on my MC and they work just fine with 235/35 front and 256/30 rear tyres.

But diameter isn't going to be your problem, it's the ET on those rear wheels. Standard rears for a 3.0Si are 8.5Jx18 ET50, so ET27 is going to sit 23mm further out even before you allow for another inch of rim on a 9.5J - I can only see that rubbing badly whatever tyre is fitted!

Probably worth putting the figures in on here to get an idea of the difference:- https://www.willtheyfit.com/

Presumably your choice of CSLs is because of how they look. If so there are plenty of Replicas around in different sizes with different offsets.

Good luck anyway. :thumbsup:
 
I'm a bit confused about these measurements as well. I guess that is due to the fact that these are OEM sizes. Are you sure you do not want to invest in aftermarket tires? They are much better, in my opinion.
 
IMG_20210220_081002.jpg

That's standard 'sport' suspension, E86 3.0si, 19x9.5 et 38 with a 265/30x19....

At a push, in thinking I can get a 275/30x19 on there, but if I had lowered suspension, or a lower wheel ET.... It would be getting owefully tight
 
You must log in or register to reply here.
Back
Top Bottom