That is funny. When I let the air out of the tire, it smelled completely different than any other tires I have deflated. I bet it was nitrogen.

I have been told by salesmen at American Discount Tire that the nitrogen slows down the escaping air so the tires maintain their correct pressure over a longer peroid of time. Also, the nitrogen maintains its temperature, so the tires keep a more consistant PSI when they get warm. The people at American Discount Tire also said that they would NOT fill it completely with nitrogen. They use a ratio of something like 20% nitrogen and 80% air.

Anyway, that is what I was told.

 

Regular air is already 78% Nitrogen.

The only reason that race-teams use pure nitrogen in tires is that they can accurately calculate the pressure changes as the tires heat up. A pure gas obeys the pressure/tempurate gas laws more exactly than a varied mix of Nitrogen, Oxygen, CO2, and water vapor. The variable humidity in "regular air" is probably the biggest problem since the vapor can condense inside the tire and really throw the pressure curves.

 

Its actually a pretty accurate needle gauge because I hate those pen type gauges! I don't even know why or how they manage to sell those anymore. I'll give the warning a few more days as it may need time to adjust to the change in tire pressure. If that doesn't work I'll pull the fuse and see if that forces it to reset.

 

my car just came shipping from japan, all the tyres were 25psi which seemed crazy. Just pumped then up to 37psi

 

Put more air in

 

Didn't check mine when I picked it up, but it has nitrogen. I got this card to register the car online. I'll post a new thread about this as I'm not familiar with this process and I also don't want to hijack this thread.

 

I picked up my vehicle on Friday from the dealership. The other day it was quite warm in Toronto and I was driving around and noticed the ride was a bit too stiff especially over rough roads and tracks. I checked the tire pressure and low and behold it was around 48+ psi. Well it seems that when the dealer prepped the vehicle they forgot to check and change the tire pressure. I adjusted it down to 33psi as recommended. Today I noticed the TPMS warning light on the dash is lit. Does anyone know how to reset this without having to go back to the dealership?

 

Did you deflate the tires when they were hot? If so, the cold tire pressure is now in the 20's. That is what is causing the light to turn on.

 

I found the same thing as most of you did that the tires from the dealer were over-inflated. Mine were about 38-42 psi. I toned them down to around 33 each. That was a great call. Thanks for bringing it up.

 

Has anyone compared the MPG before and after adjusting the over inflated tires?

I just bought my car two days ago and haven't had a chance to measure the tire pressure yet to see if mine were overinflated, but I'd be curious to see what kind of improvements are made in the fuel economy.