Just wondering what pressure people are running and how often you rotate.

Also the dealer stated that they put nitrogen in all their Minis before sale. I was under the impression the reason behind using nitrogen is it does not expand under heat. Well I was checking my tires this morning and when I got to the gas station to just top them off with air they read higher then when they did at home, cold.

Fronts both read 34.5 and the rears read 35. When I got the station they read 36 and 37. So I just subtracted the difference to get to the correct pressure of 38 per tire.

What Im getting at is did the dealer actually fill them with nitrogen as stated to me?

 

Nitrogen DOES expand under heat. Always check your tires when cold, not after driving. When a tire "expert" tells you 35psi, they mean when cold. No matter what you have in your tires, the pressure will be higher after driving...even for just a few miles. The reason for using Nitrogen is that the molecules are larger and tend not to leak out as fast keeping your pressure at a set point longer. You should know this though, regular air is 78% nitrogen. So I hope you didn't pay for it. I can't think of a bigger waste of money.

 

+1

 

Rotate about every 6,000 miles.

 

I rotate every 6,000 miles. I have a jack, stands and a torque wrench to DIY since it seems like a waste to pay a dealer $100 for the 20 minutes its takes to rotate them. Pressures I run are 38 all around (still on the run-flats)

 

Thanks for the posts. I did not pay extra for it so its no lose. I do check mine when cold also.

 

Pure nitrogen that is put into tires is also a dry gas unlike compressed air that has the moisture. This is the other advantage of having nitrogen vs. compressed air is the moisture will corrode the tire and wheel inside. Usually when using a nitrogen fill machine you only get about 90% nitrogen the first time when converting over to it. After several refills (i work at a dealer with a machine so i can refill my tires anytime to increase the nitrogen concentration) you will get a higher concentration. It is not a waste of money if you only paid $40 dollars which also includes a 1 year roadhazard warranty for the tires.

 

With the nitrogen being moisture-free, there is a slight benefit at most. The little bit of moisture in compressed air will not corrode a painted aluminum rim or the inside of a tire. Even a steel rim is not affected terribly by this. You ought to take a look at the salt spray/environmental testing all painted/coated metal automotive parts have to go through. If the tire was on the rim for a couple of decades, yeah there might be some deterioration inside due to moisture. Stated benefits like above make a good sales pitch for nitrogen. The greatest benefit of nitrogen is the profit in selling it.

 

There is no reason to believe that they didn't fill them with N2. As stated though, N2 is subject to the expansion/contraction with temperature. ( Ideal Gas Laws.)

Is it an impractical practice? probably. The only way to get a tire filled to 100%, theoretical, pure N2 would be to either feed and bleed it, or pull a vacuum on the wheel/tire and then inert it with N2.In abscense of either of these methods you would have to do a volumetric calc, and would probably find that the tire is actually only achieving an 85% to maybe 90% concentration of N2.

The moisture in compressed air is strictly dependent on the compressor/filter arrangement in place. Specifically the pre-filter/dryer assembly.

 

N2? Really?

The last time I was at the dealer I saw yet another sticker on a new car. N2 fillled tires. only $99.....

Last I checked I could get a 80ft^3 bottle of N2 for about $40. And a 80cf@ 3000psi = a lot of filled tires...lol

But on the whole, filling tires with N2 is a waste.

Oh and I run 38 psi cold, and rotate front to rear every 5K miles.

 

I run 40psi and I rotate my tires every other car wash. About every 2 weeks. I have 2 sets of tires and wheels ( white ). Hard to keep clean.

 

Just another data point... I run 215/45ZR17's (Michelin Pilot Sport AR Plus) on JCW wheels, keep'em at 39psi. I find that the rear tires tend to lose some pressure vs. the fronts. Likely due to the front-wheel-drive causing more friction on the front wheels.

I'll be rotating every 5k miles (just easier to remember). And they're uni-directional so I figure a a more frequent change couldn't hurt.

I went with black wheels (contrary to everything I've ever done).... But they look clean all the time!

 

Oh... While we're on the subject, anyone know the torque setting for tightening the lug nuts?

 

New Gen: 103ft lb (17mm socket)



If you are going to rotate - do it often - use the alignment tool linked in my sig to make it easy.

 

+2

 

I had to remove my wheels a couple weeks ago and didn't know the proper torque setting so I torqued them at 80. Is this going to cause a problem? I can't go and easily retorque them because the torque wrench belongs to someone else.

 

and of course plain old air is already 78% nitrogen anyway . . .

 

I rotate the tires my self aver 6000, or once a year, which ever comes first. Nice to have a torque wrench to make sure the wheels stay on without getting warped.

 

Yes it could. You can pull into any auto tire store and they will torque them for you, free most likely. Correct values are always in owner's manuals. Look under "tightening torgue" in the MINI manual index. It leads to page 134 in my 2010 manual.

We had our new wheels come loose when under torqued to the older 1st Gen MINI spec. Started feeling something in corners on a long trip, stopped and checked them and several wheels had come way loose........... And that was a tire store's work.

 

Thanks for the info. Got your PM too.

Went by my uncle's house and borrowed his wrench and tightened them to spec. While I was at it, I checked the front wheels too and found them to be loose. Not sure why since I have never taken them off....guess they came like that from the dealership. Anyway, I tightened them all to 103 lbs.

 

+1 on this. (See http://en.wikipedia.org/wiki/Gas_composition) There is no way a 5 or 10 percent higher concentration of nitrogen than the 78% found in air would have any noticeable effects. I just removed a set of tires from some 30-year-old Ronals that were always filled with air. The inner surfaces of the wheels were pristine. Anyone claiming benefits to filling tires with nitrogen, whether they really do it or are just pulling your leg, should be challenged with the facts.

steve s
(edgar)