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BMW E85 and E86 Wheels and Tyres Thread

Alloy wheels and tyre discussion
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Mind Bomb
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BMW E85 and E86 Wheels and Tyres Thread

Post by Mind Bomb » Mon Nov 11, 2019 11:05 pm

kis wrote: Mon Jul 09, 2018 10:20 am
18” Tyre Sizes
Changing tyre sizes is also an option for those with 18” wheels. This could be because of a complex suspension and low spring set up, or simply to save some money on opting for slightly thinner tyres. The fronts can be changed from standard 225/40/18 to 215/40/18 (narrower) or 215/45/18 (narrower and for increased sidewall… comfort). Rear wheels as standard are 255/35/18 and this could be changed to 245/35/18 (narrower) or 245/40/18 (narrower and for increased sidewall… comfort).

If you do opt for increased sidewall on the fronts or the rears there is always a chance you may experience some rubbing. Lots can affect this such as road conditions, condition / age of suspension, whether you have lowering springs, if you’ve got spacers, etc. etc.
Its taken me most of the evening reading your excellent post Kis. I'm particularly interested in the above section on increasing the sidewall size for a little added comfort. (i have a 51 year old spine!)

if i change the tyres, currently the standard sizes (225/40/18 & 255/35/18) with the intention of increasing the sidewall to 45 and 40 respectively, do i have to have the narrower tyre sizes you mention above?

ie. can i run 225/45/18 & 255/40/18 or must they be 215/45/18 and & 245/40/18 (is the narrower size recommended to lessen the chance of rubbing?)

I appreciate i could make life simple by changing the wheels to 17 inchers but the 18s i currently have looks so damn cool ( style 135 i believe)

cheers, Dani
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BMW E85 and E86 Wheels and Tyres Thread

Post by z4pilot » Tue Nov 12, 2019 11:30 am

Mind Bomb wrote: Mon Nov 11, 2019 11:05 pm
kis wrote: Mon Jul 09, 2018 10:20 am
18” Tyre Sizes
Changing tyre sizes is also an option for those with 18” wheels. This could be because of a complex suspension and low spring set up, or simply to save some money on opting for slightly thinner tyres. The fronts can be changed from standard 225/40/18 to 215/40/18 (narrower) or 215/45/18 (narrower and for increased sidewall… comfort). Rear wheels as standard are 255/35/18 and this could be changed to 245/35/18 (narrower) or 245/40/18 (narrower and for increased sidewall… comfort).

If you do opt for increased sidewall on the fronts or the rears there is always a chance you may experience some rubbing. Lots can affect this such as road conditions, condition / age of suspension, whether you have lowering springs, if you’ve got spacers, etc. etc.
Its taken me most of the evening reading your excellent post Kis. I'm particularly interested in the above section on increasing the sidewall size for a little added comfort. (i have a 51 year old spine!)

if i change the tyres, currently the standard sizes (225/40/18 & 255/35/18) with the intention of increasing the sidewall to 45 and 40 respectively, do i have to have the narrower tyre sizes you mention above?

ie. can i run 225/45/18 & 255/40/18 or must they be 215/45/18 and & 245/40/18 (is the narrower size recommended to lessen the chance of rubbing?)

I appreciate i could make life simple by changing the wheels to 17 inchers but the 18s i currently have looks so damn cool ( style 135 i believe)

cheers, Dani
Arch clearance notwithstanding, there's two things to consider if you increase the depth of your sidewalls, the aesthetics and speedometer accuracy. Assuming you're happy with the looks, then yes, you can fit 255 40 tyres, but you need to check that the overall rolling diameter doesn't negatively impact your speedo reading. 245 40 is good compromise between increased comfort and impact upon your speedo accuracy - in fact you would probably find that 245 40 would pretty much make your speedometer spot on.

Use https://www.willtheyfit.com to check, as it includes a speedo impact calculation when you change the tyre parameters
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BMW E85 and E86 Wheels and Tyres Thread

Post by Mind Bomb » Tue Nov 12, 2019 12:15 pm

thankyou z4pilot, appreciate that. The speedo accuracy 'difference' isnt outrageous it seems..... I'd rather it was lower than higher for obvious reasons.
this is from 255/35 to the suggested 245 40 (for the rears)

Theres a great little tyre shop in Herne bay (not far from me), i should pop down there and let them confuse me even more with loads of numbers.... ;)
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BMW E85 and E86 Wheels and Tyres Thread

Post by kis » Tue Nov 12, 2019 12:35 pm

I've just done the same thing! :rofl:
I've got a bit more info, so I used the same tyre width but only changed the aspect ratio (rear wheel in the staggered size).

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The experience I'd give you is that the rears were perfect (using 255/40/18). The fronts however caused me some arch rub (using 225/45/18).

So IMO if I were getting fresh rubber I'd stick to the M sizes for the rear so 255/40/18 :thumbsup:

The fronts I'm not so sure! IMO the rear sidewall gives the most comfort improvement as you're virtually sitting on the rear axle. So you could opt to go 215/45/18 for the front but theres no guarantee that you 100% alleviate the arch rubbing.

That being said my suspension is original and a decade old (I think, unless it was changed by a previous owner). So it will be a bit tired and that may be exasperating my front arch rub.

From what I recall some people have no problem running the increased aspect ratio (and keeping the tyre width) so in essence using OEM Z4 M sizes. Others like me did...

If I were getting new tyres with my current suspension set up (I need to get my new suspension fitted!) then I'd go 225/40/18 and 255/40/18

Hope this helps!
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BMW E85 and E86 Wheels and Tyres Thread

Post by mgrlane » Tue Nov 12, 2019 12:44 pm

Great post. Thank you.

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BMW E85 and E86 Wheels and Tyres Thread

Post by Mind Bomb » Tue Nov 12, 2019 4:30 pm

thanks for taking the time to respond Kis! especially after your mammouth original post!

that all makes perfect sense. in theory I should be able to go with the 'M sizes' - suspension condition dependant. The car has brand new springs thanks to 'SamP84', I can get the shocks checked out before i make any decision. But failing that i can up the rears first and see how much difference that makes.
(i should mention that the car has M Sport suspension - im assuming thats the same as an M....)

the great thing about the 'willtheyfit' site 'z4pilot' posted above is that it gives the 'Arch gap loss' so that gives me an idea on how much space is needed to up any size.... the 'ride height gain' is also mention, raid=sing the car a little would be fine - i also have 51 year old knees !!!

cheers!
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BMW E85 and E86 Wheels and Tyres Thread

Post by enuff_zed » Mon Mar 09, 2020 3:32 pm

Only just come across this thread and it is a great source of info. Thanks for the time spent in kicking it all off.

The reason I find myself here is that wifey's newly acquired 2.5i needs the MV2s refurbishing and I'm looking to swap out the 'Landsails' for something much better at the same time.
In another thread I have mentioned the rear wheels looking as though they have a much more pronounced dish to them. At this point I have not had the opportunity to remove them and read the numbers, so there may be some more work required on tyre sizes once I do that.
However, at present we have 245/40x18s on both front and rear.
They don't look too stretched at either end, so I suspect the rim widths are close to being the same regardless of offset.

My problem is that I cannot find mention anywhere of having anything wider than 225/40 on the front?

Whilst Val says the car feels fine and does not feel it is too heavy on the front, I wonder whether the overall balance would be better with 225/40 at the front instead of 245/40?

Cost is not a governing factor here, I just want to be sure the dynamic balance is the safest it can be.

All thoughts and suggestions would be gratefully received.
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BMW E85 and E86 Wheels and Tyres Thread

Post by Mr Tidy » Mon Mar 09, 2020 9:35 pm

Well the original BMW MV2s were 8Jx18 fronts and 8.5Jx18 rears and were fitted with 225/40x18 front tyres and 255/35x18 rears.

So if those are the wheel sizes your OH's car has those are the sizes it would have originally had unless you want to go for 245/40x18 rears for a bit more comfort which "mr_wilks" does, and given the number of Z4s he has owned I'd probably go along with that!

If the wheels turn out to be replicas (or are even genuine MV2s but all fronts) and are all 8Jx18 I'd put 225/40x18 tyres all round. I'm sure I read somewhere that a "square" set-up usually handles better with less understeer.

I certainly wouldn't worry about 225s not giving enough grip. My daily is a 330i SE and only has 225 tyres all round but never feels short of grip!

But those are just my thoughts FWIW.

Whatever you go for will be better than Landsails. :lol:
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BMW E85 and E86 Wheels and Tyres Thread

Post by enuff_zed » Tue Mar 10, 2020 9:52 am

Mr Tidy wrote: Mon Mar 09, 2020 9:35 pm Well the original BMW MV2s were 8Jx18 fronts and 8.5Jx18 rears and were fitted with 225/40x18 front tyres and 255/35x18 rears.

So if those are the wheel sizes your OH's car has those are the sizes it would have originally had unless you want to go for 245/40x18 rears for a bit more comfort which "mr_wilks" does, and given the number of Z4s he has owned I'd probably go along with that!

If the wheels turn out to be replicas (or are even genuine MV2s but all fronts) and are all 8Jx18 I'd put 225/40x18 tyres all round. I'm sure I read somewhere that a "square" set-up usually handles better with less understeer.

I certainly wouldn't worry about 225s not giving enough grip. My daily is a 330i SE and only has 225 tyres all round but never feels short of grip!

But those are just my thoughts FWIW.

Whatever you go for will be better than Landsails. :lol:
Oh, yes the Landsails have to go!

I'm pretty sure the rears are not standard E85 fitment, but the 245s on them fit well and, as you say, the extra bit of sidewall gives a degree more comfort.
I think my main concern is whether the 245s on the front are too wide.
If you say that a square set up handles better, and wifey feels no detriment in having slightly wider tyres on the front then I'll probably stick with the 245s there as well.
I have no issue with the grip level of a 225. I know that the stagger is designed to give a little bit of understeer as most people panic and lift off, which brings it all back in line. Don't have that concern with Val, having seen her get the tail out on her 220d convertible on a wet roundabout without batting an eyelid.
So it seems there's not much in it, and it may come down to personal preference on her part (and of course the cost, with her Scottish roots!)
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BMW E85 and E86 Wheels and Tyres Thread

Post by kis » Wed Mar 11, 2020 3:03 pm

Thank you to those who commented on my original post! Even I refer to it at times! :lol:

Mr Tidy has given some good info, but I'll add a little as well (in the spirit of knowledge and sharing - by all means I'm no expert).

My understanding is that a square set up is regarded better for handling, although in the real world I'm not sure whether any of us would realise? However that being said I think the square set up is from the alloy and tyre combination. So you'd need a square set of alloys (both 8J for example). Then matching tyres to suit.

There are issues caused from over, and also under "tiring" a wheel. So while 245/40 on a 8.5J is acceptable, I'd be hesitant to put that much tyre on a 8J? I've seen some people run 215 on the front. Never usually seen people go the opposite way and add more width.

If it were me? I'd find out exactly what alloys I'm dealing with. Are they genuine? With the staggered front and rear? Or are they square?
If you're planning on keeping the MV2's style? Or fancy a change to something else? If so then it would be worth getting a cheap set online and getting them refurbished separately? MV3 or even Style 224 look great! You can then rubber them and swap wheels over at home? Then sell the original MV's and the crappy landsails in one go :thumbsup:
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BMW E85 and E86 Wheels and Tyres Thread

Post by enuff_zed » Wed Mar 11, 2020 3:38 pm

kis wrote: Wed Mar 11, 2020 3:03 pm Thank you to those who commented on my original post! Even I refer to it at times! :lol:

Mr Tidy has given some good info, but I'll add a little as well (in the spirit of knowledge and sharing - by all means I'm no expert).

My understanding is that a square set up is regarded better for handling, although in the real world I'm not sure whether any of us would realise? However that being said I think the square set up is from the alloy and tyre combination. So you'd need a square set of alloys (both 8J for example). Then matching tyres to suit.

There are issues caused from over, and also under "tiring" a wheel. So while 245/40 on a 8.5J is acceptable, I'd be hesitant to put that much tyre on a 8J? I've seen some people run 215 on the front. Never usually seen people go the opposite way and add more width.

If it were me? I'd find out exactly what alloys I'm dealing with. Are they genuine? With the staggered front and rear? Or are they square?
If you're planning on keeping the MV2's style? Or fancy a change to something else? If so then it would be worth getting a cheap set online and getting them refurbished separately? MV3 or even Style 224 look great! You can then rubber them and swap wheels over at home? Then sell the original MV's and the crappy landsails in one go :thumbsup:
Yet more excellent advice! Thank you.
I am kind of thinking back to 225 on the front tbh.
Vall likes the MV2s and I have to say the way they fill the arches, with their as yet unknown spec, looks great.
As everyone is saying, my first step must be to get a front and rear off and check the figures. The ET is not quite so relevant as the naked eye tells me they are a good fit, so it is down to the width of the rims really.
Weather looking better for this weekend so let's see if I can actually make progress :roll:

I'll repost a pic of the car here, so you can see what I mean about the way they fill the arches.
NB. The fronts are slightly turned to the left, so don't give a true picture
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BMW E85 and E86 Wheels and Tyres Thread

Post by kis » Wed Mar 11, 2020 6:05 pm

Those look staggered to me, and also fit way too good on the rear so suspect there will be a spacer at the back (suspect they are OEM as well). Anyone want to place bets? :lol:
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BMW E85 and E86 Wheels and Tyres Thread

Post by mmm-five » Wed Mar 11, 2020 6:07 pm

kis wrote: Wed Mar 11, 2020 6:05 pm Those look staggered to me, and also fit way too good on the rear so suspect there will be a spacer at the back (suspect they are OEM as well). Anyone want to place bets? :lol:
The photo makes them look like they’re proud of the arch, so a decent hump/bump at speed and you’d bend the wing.
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BMW E85 and E86 Wheels and Tyres Thread

Post by enuff_zed » Wed Mar 11, 2020 7:04 pm

mmm-five wrote: Wed Mar 11, 2020 6:07 pm
kis wrote: Wed Mar 11, 2020 6:05 pm Those look staggered to me, and also fit way too good on the rear so suspect there will be a spacer at the back (suspect they are OEM as well). Anyone want to place bets? :lol:
The photo makes them look like they’re proud of the arch, so a decent hump/bump at speed and you’d bend the wing.
Definitely not a spacer in there. I have quadruple checked as I thought there must be.
Car is on SE suspension and with the camber I'm pretty sure the travel would take it inside the wing?

Here's a better picture now I'm on my home laptop.
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BMW E85 and E86 Wheels and Tyres Thread

Post by enuff_zed » Wed Mar 11, 2020 7:09 pm

kis wrote: Wed Mar 11, 2020 6:05 pm Those look staggered to me, and also fit way too good on the rear so suspect there will be a spacer at the back (suspect they are OEM as well). Anyone want to place bets? :lol:
Hell! You made me so self-doubting I just went and checked again. There are NO spacers. Honest guv. :D
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