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Discussion Starter #1 (Edited)
Has anybody replaced the run-flats on the BMW 405M wheels?
Looking for more grip as the stock tyres cants hold the road.
I would prefer run flats as when I found a BIG roofing screw on a 45° day I drove to meetings and jobs before driving into after store hours later.
I have been told the run-flat tyres are the largest available currently installed.
These appear too small in width and surely more rubber can sit on the rims!?!?
Stock suspension as the front splitter and side blades would scrap if lowered.
Just don't want any scrubbing, understand the wider tyre will effect fuel efficiency.
Any suggestions?

Front Wheel Size: 20"x8" et36
Rear Wheel Size: 20"x8.5" et47
Front Tire Size: 225/35/R20 90Y
Rear Tire Size: 255/30/R20 92Y

I have heard the car drives better on non runflats.

What do you do when you get a flat?
Does the tyre foam\spray damage the rims internally?
Does BMW have a air compressor kit?
 

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Has anybody replaced the run-flats on the BMW 405M wheels?

yes
Looking for more grip as the stock tyres cants hold the road.
i am questioning your driving habits if you cannot keep the car on the road.
I would prefer run flats as when I found a BIG roofing screw on a 45° day I drove to meetings and jobs before driving into after store hours later.
I have been told the run-flat tyres are the largest available currently installed.
this is not true
These appear too small in width and surely more rubber can sit on the rims!?!?
225 is the standard on a 8 inch wide wheel, you can run 255's staggered in the rears
Stock suspension as the front splitter and side blades would scrap if lowered.
Just don't want any scrubbing, understand the wider tyre will effect fuel efficiency.
Any suggestions?

255 in the rear, you could also put a 235 in the front

Front Wheel Size: 20"x8" et36
Rear Wheel Size: 20"x8.5" et47
Front Tire Size: 225/35/R20 90Y
Rear Tire Size: 225/30/R20 92Y

I have heard the car drives better on non runflats.
this is true, the extra stiff sidewall on run-flats is not ideal, there is a trade off with tires, the ability to run flat lose the feel of the road

What do you do when you get a flat?
slime plus the inflator will get you back on the road after a puncture, but you will need to plug it within 30 minutes or replace the whole tire as it will not balance in the future
Does the tyre foam\spray damage the rims internally?
jury is out on this, some say yes, others no
Does BMW have a air compressor kit
yes but you should prolly get the continental kit, seems more durable
?
answers in bold
 

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Discussion Starter #3 (Edited)
Hi Shickadance
I've updated as the rears are 255 not 225...
The car stays on the road but the car spins up in a straight line breaking traction. Was thinking of getting more power but the car can't get the current to the ground. M3 tyres are much bigger but without the pumped guards they will not fit on a 340i surely?
Previous car with much more torque and 140kw more with wider rubber accelerated fast.

Pirelli and Bridgestone today emailed me saying nothing bigger in run flats. So wondered what non runflats sizes would be best without scrubbing. Awaiting other manufacturers

Yeah I like the runflats benefits and not the idea of no spare tyre or the maybes about the repairs and damage.

Thanks for the info.

Definitely not a clear cut to change Over
 

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Hi Shickadance
I've updated as the rears are 255 not 225...
The car stays on the road but the car spins up in a straight line breaking traction. Was thinking of getting more power but the car can't get the current to the ground. M3 tyres are much bigger but without the pumped guards they will not fit on a 340i surely?
Previous car with much more torque and 140kw more with wider rubber accelerated fast.

Pirelli and Bridgestone today emailed me saying nothing bigger in run flats. So wondered what non runflats sizes would be best without scrubbing. Awaiting other manufacturers

Yeah I like the runflats benefits and not the idea of no spare tyre or the maybes about the repairs and damage.

Thanks for the info.

Definitely not a clear cut to change Over
are your tires bald? loose gravel? can you explain in more detail, this really ought to not be happening.
 

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You could set your Google to answer this, but the long/short is:

Michelin PSS for warmish weather
Conti DWS for all season play

Here in the US of A, Tirerack is a preferred vendor with much add'l info on available shoes. Those above are NOT run flats. [here] is what to do about that.

Also check your alignment and condition of suspension bushings etc. Re-torque everything to spec. There!
 

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Discussion Starter #6
I'll check that tirerack out. As my googling was on our tyre spelling and likely more hits on your tires spelling.
Great idea about the alignment. Many years ago a brand new car on one rear wheel had toeout and when corrected made a huge difference.
These are brand new at the moment and will only slip more with age.
 

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Discussion Starter #7
Tirerack US model has 18 inch standard and Australia has 19 inch.
I've now 20 inch and not listed.
Guess best await tyre manufacturers to email back
 
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