Just got new shoes installed on my R model and the car is skittish as hell, bouncing all over the place and not confidence inspiring. TPMS reports 40psi, I was running 36psi on the old Pirelli's. What's the recommended cold tire pressure for the 20" 4S for our car?

 

Some people talk of waiting 50 miles for the mold release compound to wear off, though I’ve never really noticed it. I run 38psi in my 19” PS4S.

 

I used to run 38 on my '19s but now run 36. Summer in Vegas almost impossible to get accurate pressure when tires are hot just sitting around.

 

36 pounds of nitrogen all four corners, year round.

MM

 

35 psi cold start most of the year They warm to 38 or so after driving in summer heat. Winter I bump it up to 37 or so. When stored for overwinter I put them around 42-44 to decrease flat spot development.

 

It's not uncommon for new tyres to be slippery at first, it is actually the cause of the occasional accidents as the braking could be compromised (probably more pre ABS).

But while I have you, my Michelin PSSes seem to have compromised traction recently, the back end is stepping out at very little provocation and it seems to be something that has only been happening for the past few weeks (we did get a bit of rain a few weeks ago after a prolonged dry spell, maybe it bought crud up to the road surface?). They'd have about 6,000 miles on them. Would that be normal?

 

PSS should be nicely worn in at 6,000 miles and have maximum grip, so I vote for the rain bringing road crud (oil, grease etc) to the top.
I see it from time to time in my neck of the woods - a bit of rain following a long dry spell and you can see froth and bubbles on the road surface especially on roundabouts. When I see that tell-tale froth I take it real easy!

 

Yeah i thought so too. Maybe if we get some decent follow up rain it will clear it off a bit. I'm getting pretty used to seeing the yellow light up on the dash, reminds me of my XKR days. I dont mind the back stepping out but I'm being careful with the lateral grip especially exiting roundabouts. We have had a few nasty accidents locally since that rain, two lots of accidents where 3 people were killed in each.

 

Thanks guys, I'll set to 36 tomorrow and report back. Hopefully they behave better.

 

Yep, I have had MPS4S for some three years now and I find 35/36 PSI to be the best balance between grip and ride comfort.