The door label tire pressure recommendations are for the OEM tires provided with the car. That much I know, so when you put on a winter tire, where exactly do you get the ideal pressure from? FYI I am running sottozero 2 run flat winter tires, stock 17 for a CM.

 

The 2011 Countryman manual for ALL4/S says 32 psi for 205/55-17 M&S runflats driven below 100 mph. Note that 32 is at ambient temperature with a tire that has been at rest for at least two hours. If you set your pressures inside a garage you might want to add a few lbs. if it is colder outside than in the garage.

 

2012 all4

i use a tire pyrometer to set pressures

my oem tires, pirelli summer 225/45R18, call for same ... 32 psi ... tire pyrometer said 40 front 36 rear

replaced with 225/50R18 michelin pilot super sports ... pyrometer said 42 front 37 rear

winters ... 205/70R16 dunlops ... pyrometer said 40 front and 35 rear

all pressure settings estsblished with mostly full tank and 2 passengers in front

 

Let's not confuse cold and warm pressures.

 

those are the final cold pressures ... set hot with pyrometer, then checked pressure next morning so as to have cold pressures for future

 

Thanks for the clarification. MINI must be aiming for driving comfort on the Countryman.

 

"pyrometer said 40 front and 35 rear"

Not sure I understand this, how does it determine the pressure? Based on temperature and what other variables?

 

the goal is even temperature across the tread

when i started @ 32 psi cold (book pressure) in all tires, after some spirited driving, there was a 50F difference between the edges (inner and outer) and the center on the front and 44F on the rears, indicating underinflation

i added 5 psi to all tires and drove some more and measured again ... rears were even across, fronts still cooler in center

added more air to fronts, drive more

repeat until even temp achieved across all tires

i ended up reducing the rears a couple psi as they showed to be over inflated in later measurements

if you see the temp higher in the center, that indicates overinflation and you would let some air out

end of story ... all 12 tires i have had on the car are wearing evenly across the entire tread

handling and ride are much improved

note that the pressure measured hot is not really important ... you need to measure again after the tires cool to ambient temperature and that becomes your new set to pressure

 

And don't forget that once the tire is "cold" (at ambient temperature), the pressure should be at or below the Max Tire Inflation Pressure Reading molded on the side of the tire. Never above that reading when cold.