auzoom

There are 2 main reasons people use nitrogen in tyres.

The first is the fact its inert. For this reason it wont react with rubber and supposedly gives you longer tyre life.

The second is moisture content. When a tyre expands under heat, the major cause is the water in the tyre expanding. Nitrogen expands under heat, just nowhere near as much as water and more predictably. As there is almost zero moisture in your tyre compared to air, you have much less and more predictable expansion.

Thats my understanding of using nitrogen in tyres. I have used it as Kall mentioned previously but I got fed up with not being able to play with pressures on the track (no nitrogen handy).

As for you 50psi reading, if you were told they were set to 38 and after a 15k trip on the road they were at 50 then something is deeply deeply wrong. I could begin to get 12psi increase in pressure on the track under "race" conditions, let alone on the road.

Hope that helps.

Cheers

Andrew

Cromax

Something is reacting in the air mixture inside the tyre and causing the expansion ... either that or your tyre pressure metre isn't reading it right.

Have you tried using another measurment device?

enforcer

Two very good points of view. First, I doubt its the gauge because they used the same one to put the nitrogen in a month ago. Thats not to say it's become faulty since then. A second calbration test is in order.

Second, an increase from 38 to 50 psi over 15'ks (even on a hot day) dosen't sound right - even more so for nitrogen. An increase of 5 - 6 psi at a track or driving on a hot day is realistic....but 12????

I hope there's been no distorted tyre wear in the past 1,000 k's, otherwise I'm in trouble....

enforcer

Tyres checked and the two rears were 44psi and the fronts were 40???

Allowing + 6psi for a hot day would explain the 50 psi. Anyhow, we brought them into line at 40 psi all round it should be good from here....

JAT1

Further investigation required but tonight i have found a reputable company that will sell, fit and balance the MAXXIS for $149 a piece. they are 235/40/18's. Not bad but i have to follow up on Monday...oh and apparently they are new??!! this is what i need to make sure

Black-8

also check the manufacturing date, make sure the code is higher than 0802 (see http://www.carbibles.com/tyre_bible.html)

JAT1

is this relevant to Australia? it suggests the marks are for america and europe. Do australian manufactures have this e mark? if so what number should i be looking for?

enforcer

$149 each? It sounds too good to be true.

I was lucky enough to be present when my MAXXIS were delivered to Bob Jane.

The DOT code on my 235/40/R18s is 4207, which is the 42nd week of 2007 and are less than 4 months old.

As Black 8 points out, check the number, if they are less than 12 months old grab them...and to clarify DOT codes are Universal.

auzoom

1. Yes its still relevant, any tyre that is sold in the US or Europe has to have it now.

2. A tyre stamped 0802 is 6 years old. As the page states, if the date on your car is older than this "Change your tyres", not "dont buy these tyres". As a rule of thumb I wont buy a road tyre that is more than 2 years old as I expect to run them for another 2...and thats as old as I would like to have a tyre.

Cheers

Andrew

JAT1

brilliant, thanks for the tips guys, i never knew what all those numbers and marking were for. The tyres on my car now seem to be very old so its time for a change.

Not to sound like an old woman but "You learn something new everyday"