E89 with 8" 326M's all round - what tyre sizes to go for

MACK

Lifer
Manchester
Hi, after trying my 18" Gloss black Zito 935's (F 8.5" & R 9.5" with tyre sizes 225/45 and 255/40) from my E85 on our recently acquired E89, I reverted back to the 326's it came with a few weeks ago for a few reasons.

1, I just wasn't feeling the white car with black wheels look and I just love the look of the 326's on an E89, particularly white E89's.

2, With the Zito's on (with Goodyear F1 tyres with a 5% larger sidewall than standard, 225/45 & 255/40) the car felt over tyred. It would roll more than it does with the 326's and the steering just wasn't anywhere near as responsive. I recently fitted a B12 Kit to the E89 and with this on the car almost felt too comfy on the Zito's for something that claims to be a sports car, the ride was almost saloon car like, which surprised me as I thought the B12 Kit would make the ride harder than the 70K M Sport stuff it came with. The B12 kit did reduce the roll somewhat but probably not to the level of the standard M Sport suspension and 326's with Bridgestone RFT's. I did try the Goodyears with various tyre pressures including the standard quoted RFT pressures and even slightly higher, but I just couldn't get rid of the extra roll, which led me to the conclusion it can only be too much height in the sidewalls.

I've had the 326's on a few weeks now and a trip to the supermarket soon confirmed what I already knew. It handled much better on the 19's with standard tyre sizes, but of course what I didn't like was the bloody RFT tyres.

Which finally leads me on to point of my thread. 😁
I have a bit of a dilemma, my car came with four 8" 326's (4 fronts) instead of 2 9" jobbies at the rear. So keeping the current rear size 255/30 really doesn't fly as they are really are too wide for an 8" wheel. I was initially thinking F 225/35 & R 245/35 but even 245's are about as large as your recommended to go on an 8". So I started thinking about a square set up of 235/35 all round, which seems on the face of it to have a few benefits.

1, The Goodyear F1 Supersports in 235/35 I've been looking at are anything up to £30 cheaper a corner than the 225/245 option.

2, They do increase the sidewall over the superskinny standard setup by F 3mm & R 6 mm which would probably be a good thing, without increase it so much I get the issues I'm having with my other wheels/tyres.

3, Running a square setup should in theory reduce the car's understeer.

The only real draw back I can see is that running a 235 at the rear won't look too good aesthetically and might not be able to handle the car's power/torque especially if its remapped to something close to 280 Bhp, which is the plan. That said there's plenty of M135i etc running anything up to 400 BHP on 245's at the rear, so its probably not too much of an issue.

Thoughts anyone?
 
Trying to cure a E89 of body roll simply by switching wheels, tyres, tyre pressures is not gonna happen in my experience.
Stiffening of suspension will do it but at what cost to comfort?
If the 3 89s I've owned (tried Se, Msport, H&Rs & adaotive) I have to say the adaptive does do what it sets out to do & worth getting a ride / drive in one at some point to see if it hits the spot you are aiming for with yours.
 
mr wilks said:
Trying to cure a E89 of body roll simply by switching wheels, tyres, tyre pressures is not gonna happen in my experience.
Stiffening of suspension will do it but at what cost to comfort?
If the 3 89s I've owned (tried Se, Msport, H&Rs & adaotive) I have to say the adaptive does do what it sets out to do & worth getting a ride / drive in one at some point to see if it hits the spot you are aiming for with yours.

To be honest the repair costs and failure rate with the adaptive stuff on the E89 is enough to put me off. To be fair the B12 kit has done a really good job in that department and it alone is probably enough for most people in terms of improving ride,handling and body control. That said I think with a combination of boredom (with lock down) and curiosity I might try a set of uprated anti roll bars and M3 front control arms just to see what improvement is reasonably achievable on an E89 without breaking the bank.

I'm especially curious when it comes to the ARB's. Particularly at at the rear, the E89 has the same size (19mm) as an E85 with M Sport suspension. the M runs a 21.5mm. With all the extra heft of the folding hardtop on an E89 you would of thought something beefier could easily have been spec'd. Both the Eibach and H&R kits for the E89 come with a 21mm rear and 28/27mm front (standard front is 26.5mm) so could be fun to try a kit, that said it might also be awful and coming of the same day! :D
 
MACK said:
mr wilks said:
Trying to cure a E89 of body roll simply by switching wheels, tyres, tyre pressures is not gonna happen in my experience.
Stiffening of suspension will do it but at what cost to comfort?
If the 3 89s I've owned (tried Se, Msport, H&Rs & adaotive) I have to say the adaptive does do what it sets out to do & worth getting a ride / drive in one at some point to see if it hits the spot you are aiming for with yours.

To be honest the repair costs and failure rate with the adaptive stuff on the E89 is enough to put me off. To be fair the B12 kit has done a really good job in that department and it alone is probably enough for most people in terms of improving ride,handling and body control. That said I think with a combination of boredom (with lock down) and curiosity I might try a set of uprated anti roll bars and M3 front control arms just to see what improvement is reasonably achievable on an E89 without breaking the bank.

I'm especially curious when it comes to the ARB's. Particularly at at the rear, the E89 has the same size (19mm) as an E85 with M Sport suspension. the M runs a 21.5mm. With all the extra heft of the folding hardtop on an E89 you would of thought something beefier could easily have been spec'd. Both the Eibach and H&R kits for the E89 come with a 21mm rear and 28/27mm front (standard front is 26.5mm) so could be fun to try a kit, that said it might also be awful and coming of the same day! :D

Handling is such a personal view, coming from an E85 I assume you have a different perspective than me coming from a Volvo XC70 :rofl:

I run the same 18 Zito with 235/40 and 255/35 with B8s on OE Msport springs with H&R ARBs on Conti Sports 5 and it’s pretty well controlled with little perception of body roll..

I’ve got the M3 control arms coming as the final (they all say that ) mod..

I sold my 326Ms with RF right at the beginning so can’t now compare but the ride and handling seemed dreadful..

Be interested in how it works out...
 
Well if you have time & inclination to experiment that's fair enough but to my mind you can't make a, sideboard from a piece of 3x2 :oops:
 
I do agree your never going to make it a world beater, but there's definetly room for improvement and a nice little GT car in there trying to get out😁 To think I swore to missus we wouldn't be modding this one!😂
 
MACK said:
I do agree your never going to make it a world beater, but there's definetly room for improvement and a nice little GT car in there trying to get out😁 To think I swore to missus we wouldn't be modding this one!😂

Hah that's how it always starts out :D
 
mr wilks said:
MACK said:
I do agree your never going to make it a world beater, but there's definetly room for improvement and a nice little GT car in there trying to get out😁 To think I swore to missus we wouldn't be modding this one!😂

Hah that's how it always starts out :D

Yes too much time on my hands does help either! 😁
 
Pbondar said:
MACK said:
mr wilks said:
Trying to cure a E89 of body roll simply by switching wheels, tyres, tyre pressures is not gonna happen in my experience.
Stiffening of suspension will do it but at what cost to comfort?
If the 3 89s I've owned (tried Se, Msport, H&Rs & adaotive) I have to say the adaptive does do what it sets out to do & worth getting a ride / drive in one at some point to see if it hits the spot you are aiming for with yours.

To be honest the repair costs and failure rate with the adaptive stuff on the E89 is enough to put me off. To be fair the B12 kit has done a really good job in that department and it alone is probably enough for most people in terms of improving ride,handling and body control. That said I think with a combination of boredom (with lock down) and curiosity I might try a set of uprated anti roll bars and M3 front control arms just to see what improvement is reasonably achievable on an E89 without breaking the bank.

I'm especially curious when it comes to the ARB's. Particularly at at the rear, the E89 has the same size (19mm) as an E85 with M Sport suspension. the M runs a 21.5mm. With all the extra heft of the folding hardtop on an E89 you would of thought something beefier could easily have been spec'd. Both the Eibach and H&R kits for the E89 come with a 21mm rear and 28/27mm front (standard front is 26.5mm) so could be fun to try a kit, that said it might also be awful and coming of the same day! :D

Handling is such a personal view, coming from an E85 I assume you have a different perspective than me coming from a Volvo XC70 :rofl:

I run the same 18 Zito with 235/40 and 255/35 with B8s on OE Msport springs with H&R ARBs on Conti Sports 5 and it’s pretty well controlled with little perception of body roll..

I’ve got the M3 control arms coming as the final (they all say that ) mod..

I sold my 326Ms with RF right at the beginning so can’t now compare but the ride and handling seemed dreadful..

Be interested in how it works out...

To be honest if I was feeling the gloss black wheels on a my white car I'd just be moving to the standard 18" tyre profiles. When you think about the E85M tyre sizes my Zito's are wearing, in terms of the size of the sidewalls they're the same as standard 17" wheels have on the E89, its a fair chunk of extra rubber. The fronts sidewalls are 101mm vs 90mm (94mm in the case of your 235/40 ), rears are 102mm vs 89mm. So that's up 26mm extra rubber in my sidewalls or just over 1". It also mean my cars ride height has increased by up to 13mm. So allowing for the Eibachs (which lowers circa 10mm at the front and nothing at the rear over M Sport) mines riding slightly higher than M Sport at the front and similar to SE at the back, obviously that wont be helping! :D

What tyres are you running? Mine are Goodyear F1 A3's, which do have a softer sidewall (for a performance oriented tyre) than say a PS4's or Goodyear F1 Supersport for example and I do wonder how much that becomes more and more noticeable as the sidewalls increase in size.
 
MACK said:
Pbondar said:
MACK said:
To be honest the repair costs and failure rate with the adaptive stuff on the E89 is enough to put me off. To be fair the B12 kit has done a really good job in that department and it alone is probably enough for most people in terms of improving ride,handling and body control. That said I think with a combination of boredom (with lock down) and curiosity I might try a set of uprated anti roll bars and M3 front control arms just to see what improvement is reasonably achievable on an E89 without breaking the bank.

I'm especially curious when it comes to the ARB's. Particularly at at the rear, the E89 has the same size (19mm) as an E85 with M Sport suspension. the M runs a 21.5mm. With all the extra heft of the folding hardtop on an E89 you would of thought something beefier could easily have been spec'd. Both the Eibach and H&R kits for the E89 come with a 21mm rear and 28/27mm front (standard front is 26.5mm) so could be fun to try a kit, that said it might also be awful and coming of the same day! :D

Handling is such a personal view, coming from an E85 I assume you have a different perspective than me coming from a Volvo XC70 :rofl:

I run the same 18 Zito with 235/40 and 255/35 with B8s on OE Msport springs with H&R ARBs on Conti Sports 5 and it’s pretty well controlled with little perception of body roll..

I’ve got the M3 control arms coming as the final (they all say that ) mod..

I sold my 326Ms with RF right at the beginning so can’t now compare but the ride and handling seemed dreadful..

Be interested in how it works out...

To be honest if I was feeling the gloss black wheels on a my white car I'd just be moving to the standard 18" tyre profiles. When you think about the E85M tyre sizes my Zito's are wearing, in terms of the size of the sidewalls they're the same as standard 17" wheels have on the E89, its a fair chunk of extra rubber. The fronts sidewalls are 101mm vs 90mm (94mm in the case of your 235/40 ), rears are 102mm vs 89mm. So that's up 26mm extra rubber in my sidewalls or just over 1". It also mean my cars ride height has increased by up to 13mm. So allowing for the Eibachs (which lowers circa 10mm at the front and nothing at the rear over M Sport) mines riding slightly higher than M Sport at the front and similar to SE at the back, obviously that wont be helping! :D

What tyres are you running? Mine are Goodyear F1 A3's, which do have a softer sidewall (for a performance oriented tyre) than say a PS4's or Goodyear F1 Supersport for example and I do wonder how much that becomes more and more noticeable as the sidewalls increase in size.

I’m using the Continental Sport Contact 5P optimised for asymmetric wheel sizes..

Obviously the whole geometry/wheel/tyre sizes/suspension/tyres/ARBs/chassis stiffness creates an overall effect..

Quite how an individual part affects it can only really be tested by iteratively swapping one component out at a time..

Given that broadly you’re set up was similar to mine it’s either personal perspective and/or the tyre sidewall size/the ride height result/tyre type that gives you that feeling..

I plan to swap out my 18” Zitos for a set of 17” team dynamics pro race 1.2 with similar tyres to see what effect that has as I have them already..

My gut feel is that a bit of extra sidewall by moving from 18 to 17 may actually improve the comfort without detrimental effects on handling ..we’ll have to see..
 
Pbondar said:
MACK said:
Pbondar said:
Handling is such a personal view, coming from an E85 I assume you have a different perspective than me coming from a Volvo XC70 :rofl:

I run the same 18 Zito with 235/40 and 255/35 with B8s on OE Msport springs with H&R ARBs on Conti Sports 5 and it’s pretty well controlled with little perception of body roll..

I’ve got the M3 control arms coming as the final (they all say that ) mod..

I sold my 326Ms with RF right at the beginning so can’t now compare but the ride and handling seemed dreadful..

Be interested in how it works out...

To be honest if I was feeling the gloss black wheels on a my white car I'd just be moving to the standard 18" tyre profiles. When you think about the E85M tyre sizes my Zito's are wearing, in terms of the size of the sidewalls they're the same as standard 17" wheels have on the E89, its a fair chunk of extra rubber. The fronts sidewalls are 101mm vs 90mm (94mm in the case of your 235/40 ), rears are 102mm vs 89mm. So that's up 26mm extra rubber in my sidewalls or just over 1". It also mean my cars ride height has increased by up to 13mm. So allowing for the Eibachs (which lowers circa 10mm at the front and nothing at the rear over M Sport) mines riding slightly higher than M Sport at the front and similar to SE at the back, obviously that wont be helping! :D

What tyres are you running? Mine are Goodyear F1 A3's, which do have a softer sidewall (for a performance oriented tyre) than say a PS4's or Goodyear F1 Supersport for example and I do wonder how much that becomes more and more noticeable as the sidewalls increase in size.

I’m using the Continental Sport Contact 5P optimised for asymmetric wheel sizes..

Obviously the whole geometry/wheel/tyre sizes/suspension/tyres/ARBs/chassis stiffness creates an overall effect..

Quite how an individual part affects it can only really be tested by iteratively swapping one component out at a time..

Given that broadly you’re set up was similar to mine it’s either personal perspective and/or the tyre sidewall size/the ride height result/tyre type that gives you that feeling..

I plan to swap out my 18” Zitos for a set of 17” team dynamics pro race 1.2 with similar tyres to see what effect that has as I have them already..

My gut feel is that a bit of extra sidewall by moving from 18 to 17 may actually improve the comfort without detrimental effects on handling ..we’ll have to see..

I'll be intersted to hear your thoughts on the move to 17" when you do. I'm convinced the extra rubber in the sidewall flexes too much and when coupled to other factors. Such as the softer bushings in the front arms and extra ride height, it's all just all a bit too much in the body control and steering response stakes. Although the ride is bloody comfy though! 😉
 
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