Matt Finish Wheels

Fed up with your run flats? Fancy a change of rubber?
Looking a new set of wheels? Get all your tyre/alloys info in here

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GeeDee
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Re: Matt Finish Wheels

Post by GeeDee » Wed Aug 16, 2017 4:16 pm

marco_polo wrote:
Wed Aug 16, 2017 3:55 pm

ET is the centreline of the tyre (and wheel), so moving the ET 12mm moves the tyre 12mm, assuming you're staying with 245/35/18 rears. Please don't confuse the position of the rim's external face with the tyre position.
I thought I did understand. I was working on 12mm for the reduced ET plus half the increase in wheel width ie 8.5" in lieu of 8" although I said 19mm instead of 18.35mm. :)
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Re: Matt Finish Wheels

Post by marco_polo » Wed Aug 16, 2017 4:29 pm

That's for alloy position, not tyre.

Think of the ET as the position of the tyres' tread. It's the tyres' shoulder which will hit the arch, not the alloy wheel.

The tyre tread on a 245 tyre, on a 9" ET52 rim would be in the exact same place as stock (although the alloy wheels' face would poke out an extra 12.7mm) The tyre would be a little stretched in this example.

Have a look at the tyre position on the illustration in this link: http://www.willtheyfit.com/index.php?wi ... offset2=52
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Re: Matt Finish Wheels

Post by GeeDee » Fri Aug 18, 2017 8:35 am

marco_polo wrote:
Wed Aug 16, 2017 3:55 pm
Going square (I run 245/35/18 all round) has helped kill some of the nasty understeer, but it still isn't quite right when pushing hard through Clearways. I still need more front grip.
Hi Marco
Not wishing to teach your grandmother about egg eating, but couldn't you tweak your tyre pressures and or geometry settings for this? I realise you have the M4 LCAs but did you see the adjustable top mounts BP flagged up a couple of months back?

Also, depending on the circumstances of your lap, I learnt in my karting days that just because you could take a corner flat didn't mean it was the fastest way although I appreciate that if you can get that balance spot on you would scrub off less speed.

[Granny sucking eggs MODE OFF] :D
64 plate F20 M135i-Auto used in M :drive:-LSD-Sunroof-Bells & whistles-OBDII Reader-No dipstick-Jack in boot-Tesco 99-Can be driven off without key-Bluetack on mirror sensor-Handbrake bedded in-No obvious difference between Comfort & Sports

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Re: Matt Finish Wheels

Post by marco_polo » Fri Aug 18, 2017 8:43 am

Tyre pressures were reduced to around 35psi hot (60*C), but I was over-driving the car a little I suspect. Less throttle probably would give a better line and quicker exit, I tend to get a bit 'enthusiastic' once the adrenaline starts flowing! :oops:

I would consider adjustable top mounts as long as they didn't introduce any NVH, it's still my high mileage DD for 99% of the time.
Silver F21 M135i - ManBox - HK - Adaptive + Eibach Pro's - BBS CH-R's - BMWP Drexler LSD - TMC Piggyback - M4 LCA's - aFe Dry Filter

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