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TYRES

2003 - 2009, roadster, coupe, facelift
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A1wil
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Post by A1wil » Tue Nov 12, 2019 11:21 am

Hi Guys my Z4 has run flats on it, I have only owned it for 3 weeks now. The rear wheels are practically new but the fronts have probably 3-4mm . Now I want to change them all to standard tyres eventually , has anybody changed the fronts to standard tyres and had the rears as run flats for a few months. I was hoping that the tramlining would be improved even if it was just the fronts.

Pbondar

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Post by Pbondar » Tue Nov 12, 2019 1:15 pm

Hi its illegal under UK regs to run mixed run flats and non run flats..others may argue, however if you were stopped by a suitably competent person who wanted to take it to court you would lose..

Also your insurance was invalid as it would not be in accordance with maufacturers (cars and tyres) gudielines..

Apart from that fine..

Annecdotally there have been several reports from people who have done it of bad handling /instability

Double Zero
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Post by Double Zero » Tue Nov 12, 2019 1:26 pm

Just bite the bullet on cost and change them all for non run flats, transforms the car.

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brillomaster
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Post by brillomaster » Tue Nov 12, 2019 1:49 pm

equally, others, like me , have run with a mix of runflats and non runflats, and am still here to tell the tale. I wouldn't do it for an extended period of time though - changing just the fronts while the rears are nearly new could mean a mismatch for more than a year.
Pbondar wrote: Tue Nov 12, 2019 1:15 pm Hi its illegal under UK regs to run mixed run flats and non run flats..
do you have any evidence of this? this website says the following...

https://www.motester.co.uk/mot-test-of- ... condition/

"Run flat and conventional tyres can be mixed on the same axle, although this isn’t recommended."

Pbondar

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Post by Pbondar » Tue Nov 12, 2019 3:56 pm

brillomaster wrote: Tue Nov 12, 2019 1:49 pm equally, others, like me , have run with a mix of runflats and non runflats, and am still here to tell the tale. I wouldn't do it for an extended period of time though - changing just the fronts while the rears are nearly new could mean a mismatch for more than a year.
Pbondar wrote: Tue Nov 12, 2019 1:15 pm Hi its illegal under UK regs to run mixed run flats and non run flats..
do you have any evidence of this? this website says the following...

https://www.motester.co.uk/mot-test-of- ... condition/

"Run flat and conventional tyres can be mixed on the same axle, although this isn’t recommended."
Like all these cases, for a polarised worst case view, I was looking at the event where, you lost control (for whatever reason) and injured a child that rendered it incapacitated for life..

in that context..

The Road Vehicles (Construction and Use) Regulations 1986

UK Statutory Instruments1986 No. 1078PART IICRegulation 27

says

Condition and maintenance of tyres
27.—(1) Save as provided in paragraphs (2), (3) and (4), a wheeled motor vehicle or trailer a wheel of which is fitted with a pneumatic tyre shall not be used on a road, if—

(a)the tyre is unsuitable having regard to the use to which the motor vehicle or trailer is being put or to the types of tyres fitted to its other wheels;

and then most if not all tyre manufacturers say: this is Continental

"Can I Mix Tires?

As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes (unless front and rear staggered sizes are specified by the vehicle manufacture), and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires."

So if I was a lawyer persueing you for a £10m payout I think you would be stuffed..

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buzyg
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Post by buzyg » Tue Nov 12, 2019 5:08 pm

Never a good idea to mix and match tyres. When the time comes, bite the bullet and change them all. :)
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