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Discussion Starter · #1 ·
Had the warning on the dash this morning about low tyre pressure so went about checking them all. Looked on the door pillar to find the recommended pressures are 45 psi front and 42 psi. Thought these seemed a bit high but went with it anyway however the handling seems to have taken a turn for the worse.

Long story short, what tyre pressures are you running on the 18 inch run flats. I've had a quick search about but most posts seem to be about the 17inch wheels.

Dave
 

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45/42 does seem a bit high. Maybe in the summer when the tires are hotter and have better grip. Not sure where you are located but I would guess you can bring them down to 42/40 or something that is a little more to your liking. They're runflats so they're stiff and its getting winter time so they're going to be harder and take longer to warm up. Drop them down, rest the TPMS and see how you go.
 

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What car is it; our door jamb on our f54 clubman says 2.5 bar front 2.3 rear when mid load-run flat 18" since the f56 and 55 are lighter i'd expect them to be lower not higher, my f56 on 17" cosmos was 2.4 front 2.2 rear.
 

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Discussion Starter · #4 · (Edited)
What car is it; our door jamb on our f54 clubman says 2.5 bar front 2.3 rear when mid load-run flat 18" since the f56 and 55 are lighter i'd expect them to be lower not higher, my f56 on 17" cosmos was 2.4 front 2.2 rear.

It's an F56 JCW, tried to upload a picture of the sticker but it doesn't seem to want to work.


Edit, here it is
 

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Now you have me a bit worried! I have the 18" Pirelli run flats on my JCW & I thought it was 42/39....and I bump it a wee bit since my car sits a lot. I need to relook @ my door sticker.
 

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Discussion Starter · #8 ·
The comfort or lack of I can handle, the apparent decrease in grip not so much. I'm thinking of maybe dropping a few psi and see how it improves things maybe at the expense of early tyre wear.

I'll most probably ditch the run flats anyway and go to Michelin super sports as per my last car.

Dave
 

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The comfort or lack of I can handle, the apparent decrease in grip not so much. I'm thinking of maybe dropping a few psi and see how it improves things maybe at the expense of early tyre wear.

I'll most probably ditch the run flats anyway and go to Michelin super sports as per my last car.

Dave
I'm suspecting that the lack of grip may be down to greasy roads recently, and the fairly rubbish RF Pirellis we have on this car from factory.

I asked my dealer if I could have other non run flats on dleivery, he said they won't fit them, because if you get a flat on a standard tyre, you'd be looking at a new wheel because it would get chewed up by tarmac right away!! Not sure how true that is.

So I'm with you Dave, drop the pressure a teeny bit for now, and shred those run flats as fast as possible to get new tyres!! The Michelin Super Sports do seem to be highly regarded.

I got wheel spin (a little squeal) in 4th the other day...
 

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Let lots out-our f54 cooper s is on bridgestone 18'' runflats ie the same profile as you and a heavier car and we are 2.5kpa front 2.3 rear-so i would be sure you would be safe at that! Very comfy ride in ours inspite of runflats that i hated in the past and dry grip is outstanding-700miles in-so early days!
 

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Ok, I checked my 2015 F56 JCW's sticker on the door jam....my car came with the optional 18" two-tone cup spoke wheels with Perelli runflats and my sticker "only" lists the 205/40/18 tire pressure as 42 front, 39 rear. It doesn't even list pressures for 17" tires!

So you are good to go with 42/39, no worries!

I have never had any complaints about the ride by the way, even with sport suspension...I love it!
 

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Discussion Starter · #12 ·
Ok, I checked my 2015 F56 JCW's sticker on the door jam....my car came with the optional 18" two-tone cup spoke wheels with Perelli runflats and my sticker "only" lists the 205/40/18 tire pressure as 42 front, 39 rear. It doesn't even list pressures for 17" tires!

So you are good to go with 42/39, no worries!

I have never had any complaints about the ride by the way, even with sport suspension...I love it!

Cheers for that, I'm going to go out now and let some air out.

Dave
 

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I used to run mine at around 38, 39psi but just recently checked the tyre wear and i had more tread depth in the middle of the tyre than the outsides which tells me the tyre presure is too low or is it that i drive to hard around corners???
 

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I used to run mine at around 38, 39psi but just recently checked the tyre wear and i had more tread depth in the middle of the tyre than the outsides which tells me the tyre presure is too low or is it that i drive to hard around corners???
Driving minis too hard around corners? Is that an oxymoron? There are 3 acceptable methods of mini cornering, hard, harder, hardest and all are acceptable in given circumstances. I am a runflat hater and remove them from all of my cars, not just the minis. The ride is harsh and unforgiving and unless they are super soft runflats the grip is not as good either, I tore the inner liner on set of OEM Dunlop runflats during a hard(est) corner maneuver on the MTOD last spring. Luckily for me Michelin Onsite was there and I called them and they had a set of the Michelin Pilot Sport A/S 3s there for me the next morning with a nitrogen fill for them as well. It was a different beastie after that, an exponentially better ride and vastly improved handling.
 

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Driving minis too hard around corners? Is that an oxymoron? There are 3 acceptable methods of mini cornering, hard, harder, hardest and all are acceptable in given circumstances. I am a runflat hater and remove them from all of my cars, not just the minis. The ride is harsh and unforgiving and unless they are super soft runflats the grip is not as good either, I tore the inner liner on set of OEM Dunlop runflats during a hard(est) corner maneuver on the MTOD last spring. Luckily for me Michelin Onsite was there and I called them and they had a set of the Michelin Pilot Sport A/S 3s there for me the next morning with a nitrogen fill for them as well. It was a different beastie after that, an exponentially better ride and vastly improved handling.


I plan on getting rid of the runflats as soon as the OEM Hankooks wear out.
 

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45 42 is jcw 18 inch spec press and if car is loaded its 48 45

My car felt moshy moshy when I pumped less than spec.

I stick to the spec

I would think JCW weighs more than normal MCs also the rims are not exactly the same so i would not listen to comparison from MCS rims


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Don't have my car yet but that sounds like an awful LOT of pressure for relatively small tires. On my current R56S with non-RF summer tires, I've been running 35psi both front and rear and it seems like a good balance between ride and handling.
 

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Don't have my car yet but that sounds like an awful LOT of pressure for relatively small tires. On my current R56S with non-RF summer tires, I've been running 35psi both front and rear and it seems like a good balance between ride and handling.


18inch is small? Big cars like golf GTIs have been running on 18s for a ling time


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I said "relatively small tires." 205/40/18 is pretty small volume in general guys. My 991's OEM 19" tires are 235/40's on the front and 285/35's on the rear. Their recommended pressure is 34psi front and 42 rear. Of course that car is much more rear weight biased but there's still lots more air volume in them and they're not RF's. I'm just speculating that what seem like really high suggested pressures to me might be recommended to help the RF work as intended, at the expense of ride/handling balance. Skittering around on over inflated tires does not generally make cars handle better.
I've had 5 prior MINI's and have only kept the OEM RF's on until they were worn out once. I just don't like them but it is kind of hard to rationalize throwing away a brand new set of tires. Pretty sure though I will switch to Michelin SuperSports as soon as feasible.
 
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