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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Alloy wheels and tyre discussion
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B21
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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by B21 » Tue Feb 28, 2023 6:28 pm

On the E89 it’s folklore that you should try and keep the rolling diameters front and rear within 2%

It’s alleged that the DSC can get confused on this model when the differences are too great..
We choose to go to on with this endeavour at this time and do the other things, not because they are easy, but because they are hard..

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by Pondrew » Tue Feb 28, 2023 9:46 pm

B21 wrote: Tue Feb 28, 2023 6:28 pm On the E89 it’s folklore that you should try and keep the rolling diameters front and rear within 2%

It’s alleged that the DSC can get confused on this model when the differences are too great..
I would agree after all the research I did recently on different width/ profile tyres on a BMW. I should have shares in 'willtheyfit'. :)
All good things come to those who wait. I'm really impatient which explains a lot.

F31 320i. Good car.
E89 20i Now fully dried
Z3 'free litre'. Project and a half. Complicated!
Mazda3 sold
Tatty old R56 Mini Cooper. Money pit!

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by ronk » Tue Feb 28, 2023 9:49 pm

so it is ok to raise the profile aspect 5% on the rears without changing the front without any detrimental effect ?
You don't stop playing when you get old - You get old when you stop playing!
So I bought a 35is with all the toys to play with. :thumbsup:

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by Pondrew » Tue Feb 28, 2023 10:07 pm

ronk wrote: Tue Feb 28, 2023 9:49 pm so it is ok to raise the profile aspect 5% on the rears without changing the front without any detrimental effect ?
If you are saying 255/35/19 as opposed to 255/30/19, then yes. I have had that profile on mine (with standard 225/35/19 fronts) for at least two years without any issues whatsoever. Although they are 3% larger circumference than 30 profiles.

As Peter said there is folklore (and I have not seen any proof, anywhere, so it is folklore) that the DSC is programmed at the factory for a very small tolerance in changes in tyre circumference. The DSC isn't intelligent, so if you had a larger circumference wheel/ tyre it would just think you were travelling at a % percentage slower speed so the DSC would intervene less. That's my logical take on it, anyway, with no proof whatsoever! :)
All good things come to those who wait. I'm really impatient which explains a lot.

F31 320i. Good car.
E89 20i Now fully dried
Z3 'free litre'. Project and a half. Complicated!
Mazda3 sold
Tatty old R56 Mini Cooper. Money pit!

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by True-Blue » Tue Feb 28, 2023 10:36 pm

Pondrew wrote: Tue Feb 28, 2023 10:07 pm
ronk wrote: Tue Feb 28, 2023 9:49 pm so it is ok to raise the profile aspect 5% on the rears without changing the front without any detrimental effect ?
If you are saying 255/35/19 as opposed to 255/30/19, then yes. I have had that profile on mine (with standard 225/35/19 fronts) for at least two years without any issues whatsoever. Although they are 3% larger circumference than 30 profiles.
Yep, exactly this. I’ve literally just gone down this route again today :thumbsup:
Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by B21 » Tue Feb 28, 2023 11:15 pm

My 20i had DSC issues when I unintentionally had a 2.5% difference ..it would throw transmission errors when booted very aggressively and had wheel spin..it was an auto ..I discovered they are very fussy on mismatched components…
We choose to go to on with this endeavour at this time and do the other things, not because they are easy, but because they are hard..

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by True-Blue » Tue Feb 28, 2023 11:51 pm

B21 wrote: Tue Feb 28, 2023 11:15 pm My 20i had DSC issues when I unintentionally had a 2.5% difference ..it would throw transmission errors when booted very aggressively and had wheel spin..it was an auto ..I discovered they are very fussy on mismatched components…
Both of my E89’s were manuals, and I’ve had no issues at all. Current car is N52 previous car was N20
Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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255/30/19 - ‘upgrade’ to 255/35/19 (E89)

Post by ronk » Fri Mar 03, 2023 10:31 pm

B21 wrote: Tue Feb 28, 2023 11:15 pm My 20i had DSC issues when I unintentionally had a 2.5% difference ..it would throw transmission errors when booted very aggressively and had wheel spin..it was an auto ..I discovered they are very fussy on mismatched components…
If the wheels were spinning, the system couldn't determine what size the driven wheels were?
You don't stop playing when you get old - You get old when you stop playing!
So I bought a 35is with all the toys to play with. :thumbsup:

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