I am a stickler for Michelin tires precisely filled to placard specs, AM cold. So during my 15K DIY tire rotation, I deflated my gorgeous 18” tires, trucked them to a nearby Costco and filled them with nitrogen. (very fortunate to have a wife that tolerates my odd behaviors). Of course, I reset TPMS baseline.

The result: Zero! Still get a 3 to 4 pound differential between cold AM placard pressure (35#, confirmed by an accurate mechanical gauge) and afternoon warmed up pressure. Any other tire pressure nerds out there? Would appreciate your experiences and opinions!

 

Some members of the forum actually pay for N to be put in their tires... A waste of time and money. You're breathing 78% nitrogen right now. Fill your tires to spec and forget about them.

"For most drivers of passenger cars, filling tires with nitrogen is likely not worth the cost. While nitrogen can offer some minor benefits like slightly slower pressure loss and potentially more stable tire pressure, these advantages are often negligible compared to the cost and availability issues associated with nitrogen. Regular checks and adjustments of tire pressure with regular air are generally sufficient and more cost-effective".

 

The $300 Nitrogen add on for new cars has to be one of the most insulting forms of a dealer ripoff.

 

Tires increase pressure by approximately 1 psi for every 10 deg C increase in their temperature. I set mine at the recommended 36 psi “cold” and by the time I have been cruising for a bit they will be at 40-41 psi. In “engineer speak”, if the volume does not change then the pressure is (roughly), proportional to the temperature. ie: “if the temperature goes up then so does the pressure if the volume stays the same”. You can dig up a more detailed explanation by looking up “Boyle’s Law”. Btw, temperature is expressed in degrees kelvin which is degrees Celsius plus 273. By the same law, pressures will drop in the cold and that is why we have to add air in winter. A tire that, in the autumn at 20 degrees C was 36 psi, will drop to 34 psi at 0 degrees C and 30 psi at -40 degrees C. Aren’t you glad you asked? 😂

edit: oh, by the way, “air” is already 78% nitrogen.

 

I too, am obsessed with tire pressure monitoring and never pay for nitrogen. The cars that I have purchased which allegedly were already nitrogen filled or just had green valve caps put on, showed no difference at all in temperature related pressure variations,

Dave Mac

 

You need to brush up on your thermodynamics. Kelvin is Celsius plus 273.16. I agree nitrogen is mostly a gimmick for the average driver but it does give you more stable pressures because of lower moisture, assuming of course you are adding dry nitrogen. This benefit is minimized by adding dry air. Nitrogen does diffuse through rubber more slowly but again this is minimal benefit for average driver, especially one who checks pressure on a regular basis.

This behavior is Gay-Lussac’s law, not Boyle’s law.

 

Correct you are. It’s been 50 years since I had to study that stuff so…🥸. Fixed.

 

Here you go.

 

Did you vacuumed the tires (did you remove all the air from the tires) before you filled them with nitrogen?

 

I did notice with my tires that were nitrogen filled that they seemed to lose less air over time i.e. several months than those that were not nitrogen filled.

 

I think that the guy that started selling Nitrogen to put in tires is the same guy who will charge you for changing the air in your tires if he thinks you will fall for that.
I have a nice little air compressor in my garage, and check the tires from time to time, and have not seen any significant change in pressure over the two years I have had my ES350. The air that works for me seems to be working fine for my car.

 

I bought my ES in October '23 and I STILL have not added an ounce of air (not Nitrogen filled). I'm pretty sure the dealer never added any.
Maybe this is the one good thing about Low Profile Tires

 

Referring to this as “insulting” and “ripoff” is a very kind and generous use of the English language! Little wonder the word “stealership” entered the lexicon!

 

It's insulting because they assume we just fell off the Turnip Truck. Personally I'm sitting just fine on my Turnip Truck

 

Deja vu, all over again! My jogged memory recalls that I used to teach a physics class in a vocational school HVAC course, 4 decades ago. I taught heat transfer, Charles’, Boyle’s and Gay-Lussac’s laws in my sleep. So here’s the biggie: With my broad expanse of academic knowledge, why did I ask such a dumb question about nitrogen vs. garden-variety air in my tires !?! Senior moments are upon me, I guess!