So my new 2010-R56 came with stock Run Flat Pirelli 205/45/17 tires were set at 38PSI per MINI (hurt my kidneys!!) on stock suspension. Then I just installed new 215/45/17 Bridgestone 970 Pole Position All Season tires. I was thinking on running 35PSI or less, but just wondering if it will hurt the even wearing of the tire.

Advise is appreciated. Thanks!

 

I run my Michelin PSS 215/45/17 at 40 psi as per recommendation of my local installer. Ride is excellent! The radials have a softer sidewall than the RF and even at 40 psi, it feels way softer than the stock RFs. I think the higher pressure also help stiffen a PSS sidewalls and increase response during turn-ins. Although, I must say, the RF turn-in response is still tighter at 38 PSI.

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35 or a smidge higher sounds good to me.

 

I have Michelin all-season high performance tires. Recommended pressure is 30-50 psi. I put 40 psi and my tire wear has been excellent, but that could just be my driving and upkeep habits. I think Michelins might have slighly higher psi tolerances so if you go with something else I would say +1 for 35psi.

 

I wouldn't run them lower than 35. 38-40 is probably good.

 

I run mine at 34psi on my Clubman S

 

My Conti dw's are set at about 32 to 34 depending on out side temp. Nitro track tires hit the track at 24 to 26 cold. The heat up just fine. Go to harbor freight and get inferred temp gauge for about 20 bucks. When running hard you want even temps across the entire tire. At 38 cold you will be running on only the center of the tire and the outsides will be cold and greasy when you need them. The auto cross guys run higher pressures because they don't run long enough to get tires up to the proper running temps. If pressure is to low the center will be cool and the outsides hot. It is amazing what a half a pound will do.

 

When I ditched the runflats I chose 215/45/17 due to better tyre availability and pricing in that size here in the UK over 205/45/17 OEM size.

I ran Continental Sport Contact 3 which I still have on the rear and wore out the front. Now have Contact Sport 5 on the front and 5mm all round as rears wear least.

A factor in front wear was my PSI. I used to run 35 PSI and they wore more in the middle so were over inflated. Now run 33 PSI.

 

All tires are a bit different but the goal is basically the same. You want an even contact patch. You are looking for even heat on the face of the tire. Your hand is pretty sensitive to temperature too so in absence of a gage you can just touch your tires after driving for a while. If it is warm on the out sides and cool in the middle you are under inflated. If you are warm in the middle and cool on the outsides you are over inflated. Adjust the air pressure so the temperature is even across the face of each tire.

 

Since the 215/45-17 is both wider and taller than the stock 205/45-17 it will have a larger volume of air and require less pressure than the stock size. I'll just run at 34psi until I can tell if they are wearing more in the center of the tire or the outer edges and adjust from there. If the edges are wearing faster, I'll add more and if the center is wearing, I'll reduce.

 

I run 38 in my 215/45-17 PSS.