Confused about correct tire pressures

[bhoobhoo]

Hi everyone,

Enjoying my HB/W MCS. Got a question about tire pressures. The tires I got are the Dunlops 205/45 17"

They came from the dealer inflated to 33 psi.

I looked at the left door jam and it rec. 38 psi for all four.

Then I looked at the manual and it rec. 33 psi for 1-2 passengers and 38 psi if you have 4 passengers.

Then at asked a maintenance guy at the MINI dealer and he rec 38 psi even though most of the time it's just me in the car.

So now I turn to the more trustworthy opinion of the MINI2 community

Thanks

[lespurgeon]

That ride is going to be even rougher at 38 psi...

38 will give you the highest MPG, and stiffest cornering, 33 will give you a nicer ride and MAY give you better grip.

I'd try 35.

[Aqualung]

I second the 35..I am getting 26.1 mpg on my car (JCW), w/ the Dunlop Performance RFs.

I would classify myself as a moderate driver, not much tire squealing for example. 70-75 on the hwy to and from work.

[vagt6]

Look on the sidewall of the tires and you will find the recommended pressures. Inflating to the top of the range = stiffer ride. Inflating to bottom of range = slightly softer ride.

Play around with the pressures until you find what's best for your style of driving. Don't over or under inflate, it can be hazardous to your health.

good luck!

[parkerea]

Keep in mind that the tire sidewall lists the max pressure, not the recommended pressure. In addition to the issues raised by others in this tread, different pressures also cause different wear patterns -- higher pressure causes more wear in the center of the tread, lower causes more wear on the outside of the tread.

The "ideal" pressure is hard to determine. Although I have never tried it, I have heard of checking the tire contact patch by lifting a tire straight up VERY carefully so it does not slide along the ground, placing a metal plate under the tire, put a piece of carbon paper face down on the place, and carefully set the tire down. (For you youngsters, carbon paper is what we all used back in the stone age, before there were photocopiers.) It sounds plausible, but I have my doubts that the 30 PSI range is sufficient to cause carbon paper to transfer.

Still, the concept seems valid, although I have thought about other methods, like using sand instead of carbon paper, blowing the sand away with an air gun, then lifting and seeing where the sand remains. Or using plain white paper and putting paint on the tire before setting it down.

Of course, once you know the contact patch size & shape, then what? What should the contact patch look like? Since there are trade offs, I assume the desired contact patch for maximizing fuel mileage vs. handling vs. tire life may all be different.

Sorry for the long winded answer, but I just can't stop when I get on a roll.

[SteveM3]

Depends on how accurate you want to be and how much effort you are willing to spend.
To be accurate for you, your use of the Mini and your driving style you need to watch
your tyre wear. If it is even all over you have it just right. If most wear is in the center you
should lower the pressure. If most wear is on both outside edges then increase the
pressure. If the wear is uneven get the suspension geometry checked. If this is all too
much hassle then if you mainly drive on your own and you drive gentle and cruise most
of the time select the lowest figure 33. If you drive on your own but like a back road blast
as often as possible try 35 or 36. I usually find the lowest pressure on the undriven wheels
and a middle pressure on the driven wheels gives my style of driving the most even wear.

[DJC]

Try 32 PSI all round, works on my wheels. Good ride and great handling. Hope this helps, Damian.

[speedynz]

I read on here that slightly over inflating the tyre from the minimum recommended pressures can really improve the ride as it 'lifts' the tyre off of the very stiff steel sidewall that runflats need and provides a cushion of air between the tread and sidewall.

So I tried it and hey presto, a far better ride and with no compromise to handling or wear. I added 2psi, for a total of 35psi which is also nicely in between your quoted recommended pressures. Give it a go and see what you think.

Make sure tyres are cold when checking otherwise your pressures will end up all over the place.

Also if your tyres are anything like mine then top ups will be required every 2-3 weeks.

[Parc77]

mine are at 33, not too low and not to high just right, well as right as they can be on runflats