I've got an 06 MCS, and traded Bridgestone runflats for Hankook V12 Evo's about 1400 miles ago. I notice that the softer sidewalls do make a difference in handling as I could feel some minimal body roll during harder cornering that wasn't there before. The V12s seem to be nice & grippy, but the slight lean is there.

I checked tire pressure today: both passenger side tires were 29.5psi, the driver front was 31, driver rear was 30. MINIs specs are 35psi, but I think I filled to 36 or so by accident on each tire.

On the trip home it seems the cornering was much firmer than before I filled the tires. Can 4-5 psi make such a difference, or is it a placebo effect?

 

Yes it can. Play with your pressure to find the sweet spot you like and keep it there. On my maserati 3LBS is huge. Difference between sloppy handling and darting to hooked up and perfect feel. I was surprised how much it made a differnce with just a little difference. I now keep a gauge in every car and check them often.

 

Thanx for the reply 'Maser. The max pressure on the Hankooks is 50psi, MINI recommends 35psi. What's your take on inflating somewhere in between, i.e., anything wrong w/running higher pressure than MINI's specs?

From what I understand - and correct me if I'm wrong - but more pressure might = less body roll, but also less rubber on the road, and therefore slightly less grip. Am I right?

 

Max pressure is not really 50 psi if you are trying to be reasonable and drive on the street.

Over inflated tires will wear on the center tread over time and ride much more harshly.

Some owners will purposely over inflate to reduce rolling resistance but 36 to 38 psi is probably good enough. 29 psi is way too low and you will get poorer mpg and wear the edges of the treads.

Your recommended tire pressure is determined by MINI and while you can exceed it a little you don't want to run lower pressures. When the weather is warm the pressure will rise as it does once you drive around a little. The sun also warms the tires.

Check pressures first thing in the morning or during the coolest times of the day when possible.

 

Yes it can. Play with your pressure to find the sweet spot you like and keep it there. On my maserati 3LBS is huge. Difference between sloppy handling and darting to hooked up and perfect feel. I was surprised how much it made a differnce with just a little difference. I now keep a gauge in every car and check them often.

 

The max pressure listed on the tire is the maximum pressure that it can handle for any extended period and not fail. DO NOT inflate your tires to the max pressure listed on the tire. These days OEM's typically jack up pressure as high as they can in order to maximize fuel pressure. Stick to the recommended pressure +/- 2psi.

And to answer your question, 4-5 psi low can make a HUGE difference. difference.

 

I've been running 34psi front and 32psi rear on my snow tires, but I run around this with every car I have (2psi lower in rear) - but they've all been FF cars. Front engine, FWD.

 

I had a set of Evo 12 K110s on my '06 MCS previously. In my experience, lower profile tires, such as 35s/40s/45s, require a bit more air than higher profile tires. I have run as low as 36PSI, but I tend to use 38-40 PSI. 36PSI is based on a single passenger, and the higher settings account for additional persons. The higher pressures help the small sidewalls maintain shape.

 

FWIW I inflate the tires to 34psi on 215/40R17 and 32psi on 205/45R17 because air temp here is usually in the mid 30s (celsius). I'd like to think that the given tire pressures are just right given the road temp we have here. CMIIW.

 

The Mini recommended tire pressure will bear this out as well. As the profile goes lower, the pressure goes higher. For the 205/40-18's (JCW wheels), Mini recommended 36 all around. (06 cabriolet with every possible JCW option.) However, the guy I bought the car from ran 38/36 and he recommended that so that's what I've been running. 'Seems to work very well, even when pushing the car very hard. (The previous owner used to race the original Mini's when he lived in Canada.) Then, when I switch to Hankook Ventus V12 Evo's (215/40-18, I stuck with the 38/36 and that combo works very well, too. I also figure that there's more weight on the front of the car, to say nothing of the fact that the front tires are doing more than just steering the car, so it makes sense to run a bit more pressure up front.

 

We have a winner! Winter tire PSI should be higher by 3-5 PSI.

So for the OP's 35 PSI factory door sticker requirement, he can go 38-40 in the winter. Plus it gives you a buffer if you do neglect to check them frequently enough. All things being equal, a tire will lose 1 PSI a month.

 

The psi marked for your vehicle are cold psi, when checked after 12 hrs of being stationary. When you drive the car the PSI will increase at least 3 psi. So 35 psi cold will be around 38psi after a 10 miles of normal driving . Do not let air out of hot tyres to reach your given psi, Cheers

 

Don't know if you noticed or not but mini_macky posted that 11 years ago. He/she may not even have that car now.