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I think the recommended cold pressure (41/38 lbs) is too high. On other forums (eg BMW M cars), drivers using Michelin PSS and PS4S are recommending pressures around 33 cold. My own experience is that I get to 47 hot when starting with 41 cold, and at that hot pressure the PS4S loses grip. This is with ambient temps of 32C=90F.

I find 36/33 cold (est 41/36 hot) more comfortable and gives optimum grip. I have more confidence in the twisties.

I understand the increased risk of rim damage with lower pressures.

I don’t know why Ford recommend such high pressures. They are higher than other cars of similar weight and performance eg BMW M1 or M2. What’s special about the RS?

It’s been suggested to me that the high pressures are set to maximise fuel efficiency...
 

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I don’t know why Ford recommend such high pressures.
Load Rating and tire size. This is a heavy car. This is Michelin's, not just Ford engineers explanation from when the car was first introduced.
 

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The whole tire pressure and solution are somewhat complicated. Many things go into selecting the "right" tire pressure...but virtually every situation it is a tradeoff btwn wear, grip, ride, durability, and safety.

IMO, ona 2016 RS For street use w/MPSS, 42/37 cold works best. But if I were tracking then the hot pressures would be more like 40 or even 38 front, 33 to 34 rear....but the tires will wear very fast, especially front outside edges.

THE DESIGN TRADEOFFS made by Ford with limited front camber, narrow 8" 19" rims and 35 profile MPSS tires on a 3500# car means Michelin had to tweak their std design and require higher pressures to meet mileage, fuel economy, performance, and handling as defined by Ford.

Fully agree, on almost every other rear wheel or AWD car I've owned running MPSS tires, hot pressures of
38 -40 psi front, 34-36 rear worked best.
 

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I find it interesting that you guys find 42 good on the fronts for PS2s, as I thought the car felt rather sloppy and unresponsive compared to when I used 45 (cold). I had a LOT more confidence in the car then. Maybe down to driving style?
 

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I'm running Mountune black springs and a WL 22mm rear sway bar. 45 cold was a terrible ride and tended to wear outer edges. You're right about driving style and ride expectations. I'm not looking for a totally flat cornering attitude but max grip...41- 42 cold worked best on my roads.
 

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I tried the 'how low can you go' approach for street comfort and ended up back at 41 / 38 cold

No gain in comfort at ~ 36 psi compared to the above and I had poor cornering feel
 
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