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Another tyre thread! But I have done a search first!

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
Captain Vimes
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Another tyre thread! But I have done a search first!

Post by Captain Vimes » Mon Aug 14, 2017 10:00 am

Hi all

I have been the proud owner of a 2013 sDrive20i MSport for three months now and loving it!

I always intended swaping the 19 inch Potenza run-flats it came with for 'normal' tyres when they need chaning, however they are nearly new! It's my only car and I do about 15k miles a year, 75% on the motorway. So now I am thinking about swaping sooner, and indeed dropping down to 18 inch wheels for better comfort and lower road noise. I use it as an everyday car, so not so concerned about looks.

I've not driven a Z4 on anything other than 19 inch run-flats so my question is, how much does it improve the noise level? Not too worried about comfort, it's OK as it is although it would be a bit nicer to have more give in the tyres, it is very much about the noise at 70 to 80mph.

Can anyone enlighten me?

JB

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Another tyre thread! But I have done a search first!

Post by Hellequin » Mon Aug 14, 2017 10:42 am

I changed the runflats to Cooper non-runflats on my 2.5 and the difference in noise is marvellous. Especially noticeable on the M25 near Heathrow where the surface is concrete, I think
Last edited by Hellequin on Mon Aug 14, 2017 11:41 am, edited 1 time in total.
59 plate sDrive23i 2.5

Captain Vimes
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Post by Captain Vimes » Mon Aug 14, 2017 11:01 am

Cheers. That confirm's changing the tyres then I think.

Now I just need to decid if to change the wheels. Are yours 18's or 19's?

Vimes

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Another tyre thread! But I have done a search first!

Post by bob4333 » Mon Aug 14, 2017 11:03 am

Move away from RFT's and you'll definitely notice extra give in the tyre walls as the tyres now make more of a contribution to your car's suspension.

I chose to stay on 19's but had similar objectives in mind to yourself when I swapped. I had a significant expectation in terms of noise reduction which was only partly met. Subjectively, tyre noise does seem a little less (even commented on by my wife - without any prompting) but it's not a night and day change. Running 18's may be different.

I think it was Maniac who pointed out on another thread that your ears are pretty close to the rear axle and road wheels, so noise attenuation may not be huge. It'll never be like driving a saloon car. Plus of course, the road surface you're driving on is the biggest variable.

And then there's the question of what pressures to run them on - a subject well covered on the forum...............

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Post by Captain Vimes » Mon Aug 14, 2017 1:53 pm

Cheers.

Fully realise it will not be a quite as my 'old' Mondeo, but want to make sure I make the most suitable changes to get the best out of the car for the purpose I will use it the most
.

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Post by Hellequin » Mon Aug 14, 2017 3:19 pm

My wheels are 18s
59 plate sDrive23i 2.5

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Post by Freebster » Mon Aug 14, 2017 7:24 pm

I did not notice any difference going from 18" run flats to 19" run flats. Both sets were running the same Bridgestone RE050.
You will probably hear a bigger difference going from run flats to normal tyres.

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Another tyre thread! But I have done a search first!

Post by mcbutler » Mon Aug 14, 2017 10:14 pm

Go for Michelin Pilot Sport 4, amazing tyre, very highly rated. I run these and they are TRULY amazing..
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Post by Captain Vimes » Mon Aug 14, 2017 10:49 pm

Thanks for the responses so far. I'm feeling pretty confident that switching from 19 inch run-flats to 18 inch normal wheels and tyres should give me a noticeably quieter ride.

Now I just need to find the right wheels and tyres! Tyre advice aplenty on here, but I need to research wheels next.

And apart from here and eBay, any ideas where I might be most successful in selling the current 19 inch wheels? They are 326Ms with nearly new Potenzas all round.

Cheers

Vimes
Last edited by Captain Vimes on Mon Aug 14, 2017 10:52 pm, edited 1 time in total.

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Post by Captain Vimes » Mon Aug 14, 2017 10:52 pm

Here's the motor in question! I was thinking dark grey wheels.....?
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Post by SteveSmith » Mon Aug 14, 2017 11:17 pm

Just fit normal tyres to the M326's.
28i M Sport - Alpine White / Canberra Beige, 19" M359’s, H&R’s / Eibachs, BMS Stage 1 - 271bhp, Front Splitter, CF Rear Lip, Alcantara Steering Wheel and Brembo 4 pots

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Post by Busterboo » Tue Aug 15, 2017 1:12 am

Captain Vimes wrote: Mon Aug 14, 2017 10:52 pm Here's the motor in question! I was thinking dark grey wheels.....?

Image
The VO + black roof is superb.

If you keep the 326s, just check they're not cracked before you put new tyres on them.
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Another tyre thread! But I have done a search first!

Post by Captain Vimes » Tue Aug 15, 2017 1:31 pm

Ta! Waited nearly a year to get one! Had to have the black roof..... 8)

The potential cracking issue is one other reason I'm going to change. I know with non run-flats there is less chance, but I'm still taken by the idea of 18's with more sidewall for comfort.

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Post by Busterboo » Tue Aug 15, 2017 2:21 pm

Captain Vimes wrote: Tue Aug 15, 2017 1:31 pm ... but I'm still taken by the idea of 18's with more sidewall for comfort.
Remember that one of the holy grails of tyre design was wall stiffness, not least because it contributes significantly to agility & steering accuracy, which was why designers went to big wheels with shallow-walled tyres at high pressures that were stiffer than 'normal' tyres. (Big wheels & liquorice-strip tyres were/are also 'cool', but that's an entirely different game, isn't it?)

Ironically, RFTs also have stiff walls & high pressures, of course - it's part of how they work - but, as you know, some people find their performance problematic, which brings us to your 18"s and "more sidewall for comfort" ...

Several of the major manufacturers are now producing their 18" tyres in Z4 sizes as 'XL' - for heavier load and, yep, with stiffer sidewalls. (Here, "load" relates to power & performance, of course, and not only to 'driven by a big guy, with his large wife in the passenger seat & the boot full of luggage'.)

So, it may well be that, in some very good 2017 18" performance tyres, you won't find the comfort you seek. Mind you, you can always let 10psi out ... :wink:
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Another tyre thread! But I have done a search first!

Post by ph001 » Tue Aug 15, 2017 2:41 pm

Note that the 326 style wheels are also quite susceptible to cracking so:

1) You will find plenty of eager buyers on Ebay with cracked wheels wanting a replacement.
2) Fitting non-run flats will help in preventing cracking in the first place due to the far higher compliancy.
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