230deg??? Are you drifting??? If racing/DE you are overheating the tire, optimum temp should be 180 -210 depending on the tire. Drive a tidier (is that a word?) line and you wil be faster and the tire will last longer.

IMHO - As others have said the only advantage to Nitrogen, is that its dry. and that advantage is only relevant when you get near the state change of water (212 deg). But you will never see that in a street tire, so its irrelevant in that application.

The other thing I think is funny is the same tire shops that sell Nitrogen for the tires (again to keep water out), will mount the tires with water based lube…. I watched one shop smear the whole barrel of the rim with this goo… Forget a little water vapor, they are adding liquid water to your tires.

 

Sorry, feel the need to defend my honour! :P

Talk to Hoosier. The tire doesn't even start working until 175. It isn't uncommon to see a rear on a 911 get above 225. The tire overheats arount 240 (again according to hoosier). The course I run is 3 miles long and consists of 22 turns. The tarmac is brand new but can be hard on tires because of turns. PSE is on at all times so there isn't much drifting.

The fastest stock GT3 do the course in 2:16 and I was in around 2:22 with a fast lap of 2:19.

Keep in mind that many people who don't run dedicated test sessions are only measuring tire temps at the end of sessions and probably did a little bit of a cool down lap plus came into the pits. Tire temps drop rapidly and should be taken in pit lane after a hot lap to be as accurate as possible. I had to do this because hoosier suggested that I was overheating my first set causing them to split at the shoulder.

Hope this isn't interpreted as argumentative, I was just going with what the guys at Hoosier told me.

 

Easy there... you 993 guys must not be used to pushing your almost antique cars too hard. Personally, I drive flat out, and it murders street tires and brakes.

 

Let's see...fill tires with air: 78% Ni and 22% O

After a month assume ALL the O leaks out....

Refill with air ( the 22% that leaked out): .22 x 78 = 17%. 17% NI + 78% = 95% Ni and 5% O

Refill after another month: .05 x 78% = 4% Ni . 4% = 95% = 99% Ni + 1% O

And so on...after about 3 refills with air the percentage of Oxygen is negligible.

Fine for street cars if the air is reasonably dry. Track is another issue as tires are mounted and dismounted more often and heat cycles are more extreme.

 

No argument from me....

If Hoosier engineers are telling you they are good to 230deg, who am I to argue.... I guess I need to push them further than I have... I was going by the published specs.

 

My 6lb rise is after a nice easy cool-down lap. I wonder what I'm getting during a hot lap?

 

Should clarify that tire surface temps and internal temps will be different. Chances are you not going to see the internal temps drop as quickly. For checking pressure you're doing fine. It'd say you're within 1-2 psi of hot pressures.

As the outside of the tire cools the internals follow. As a practical example, your tire pressures will not have dropped all the way down between sessions but your tires surface time will be much less.

 

Every time you refill the tire, you add more moisture to the mixture further increasing the severity of the pressure delta between warm and cold.

Nitrogen has nothing to do with the gas being used. Nitrogen is simply the easiest and most abundant gas to pull from the atmosphere and is completely in-volatile and safe. It's the 'dry' air that is important. I should also note that many shop air systems have oil in their air lines to keep tools and equipment running properly even after it's been dried by a dryer. Air that you get at the gas station is almost certainly not dry.