Nitrogen instead of air

[kiks]

Enough that its firm when I kick it. But not firm enough to hurt my toe.

So its all relative to what shoe I wear on the day.

[sjm69]

Most tyre shops I find unreliable in setting pressures I'm happy with.

Agreed, that's what I don't like about the whole nitrogen idea, if you have to top up at the servo you're wasting your money.

Plus, if the main benefit (at least for a road use passenger car) is that air leaks slower, and I check my tyres regularly anyway then there is no point.

Check out http://www.racq.com.au/motoring/cars/ca ... _for_tyres for a little info.

I payed $5 per tyre and any top up is free for the life of the tyre

[senator]

Its a complete wank. Dont fall for the shit.
.

+1 especially for road tyres...... I did recently opt to have my track tyres filled with Nitrogen, it saved me burning my hands bleeding them to reduce pressure after first session.

[3rspecb]

Its a complete wank. Dont fall for the shit.
Keep tyre pressures consistent.....
Did they inflate them with you sitting in the car?
At what level was your fuel tank filled to?
How perfect is the alignment of your car?
Is every road you travel on an identical camber?
Absolute load of bullshit made to sell $0.03c of nitrogen to you as a 95% blend or so (as theyre tightarses and get all the byproducts of compressing inclusing co2, o2, oils and shit into the tanks) for $10.
Long story short, you're a sucker. The air you breathe is already 78% nitrogen. At most they aim to remove a little co2 to save from minute leaks of co2 through the permeability of the rubber. Which still happens with nitrogen at tyre joints as their nitrogen has co2 in it anyway.
That is still 100% completely separate from my first 4 points above, next time tell them no thanks, regular old air like is used in every other car tyre is fine and you'll pocket your $40 and spend it with them on refitting your tyres a few times to use as little weight as possible to balance.
Threads make me laugh.

Great post.

I still can't believe people getting rolled filling nitrogen in road tyres

[champ]

I personally... run 38f 36r.

And what is the benefit of running higher pressure at the pointy end?

[Kekotic]

I personally... run 38f 36r.

And what is the benefit of running higher pressure at the pointy end?

I always thought it was run higher at the rear for our cars? I have been following Ric's advice (or at least I think this was his advice...maybe I got it wrong) and doing 38 at the rear and 36 at the front.

[bass_straitener]

I personally... run 38f 36r.

And what is the benefit of running higher pressure at the pointy end?

I always thought it was run higher at the rear for our cars? I have been following Ric's advice (or at least I think this was his advice...maybe I got it wrong) and doing 38 at the rear and 36 at the front.

I reckon you could be wrong on that one and should be the other way around. Higher tyre pressure in the back in our cars would cause the back to be more slippery, less contact patch, causing it to step out early. Running a little bit more in the front induces more understeer which is better than oversteer. Also could be different from a wagon to sedan perspective due to weight distribution.

[smythie]

The tyre placard does suggest slightly higher in the front unless spending long hours on the highway or heavily loaded.

I have a TPMS fitted to mine so nitrogen is a waste of time for me - I check pressure and temp at the start of just about every drive and often during a drive for interest sake.

For reference, 1.5km's from home and cold to a servo down the road *might* raise the tyre pressure maybe one psi. Also remember that the 32 or so that Subaru lists on the placard is meant to be set at 21 degrees celsius.

[Kekotic]

What pressure do you run smythie?

[tkboi]

everytime i do my tyres its always a bit lower just for that bit of increased traction. so normally i drive 38 all round but if its for a spirited run the pressure gets down to around 34/32?

[kiks]

Enough that its firm when I kick it. But not firm enough to hurt my toe.

So its all relative to what shoe I wear on the day.

Ok serious answer:
On semi slicks when Im having a proper crack. 22psi front cold, 28psi rear cold. Ends up being 27ish and 33ish with rubber peeling off.
When just podding about 34 front 38 rear.

On normal road rubber:
40/40 or so. Best economy, fairly good on tyre life with a sensible wheel alignment, and only really intrusive over bridge expansion joints etc.

Much rather run a significantly higher pressure in the back. Two reasons personally.
Car feels more neutral by decreasing rear end grip a small amount. This in turn allows more confidence as the car is completely predictable. Its no slower due to the fact the rear end slip allows wheel slip which allows a good torque transfer to the front. Its a lot easier to drive ham fisted sony playstation style fast this way.

I run about 3.5mm of toe out on the rear usually. (which brings two points up) Higher pressure maintains a similar tyre form, making it fairly predictable. At lower pressures grip rates change wildly based on yaw, pitch, roll and axle bound. I find its nicer to have a consistently lower amount of predictable grip (see above) than a higher amount of rear grip that just disappears once the car levels out. Second little point here is that there is a more defined tyre footprint which allows more careful monitoring of tyre wear.

A disadvantage.
Over undulations with such a strong chassis and a minimal droop, a higher rear pressure tends to lose contact with the road more often. Under brakes with a heavy forward weight transfer this can cause premature ABS. Its enough to clench a bum cheek now and then when my middle pedal of life decides to kick at me.
Pay more attention to tyre wear and thus more money in alignment/rotations.

I use symmetrical tyres so I can swap left/right. But a set of semi's did last me 14k by being anal about levelling tyre wear.

All in all for me it revolves around changing the grip bias of the car to allow it to be more driver friendly, I've tailored the entire car as a package around the fact I want a higher front end grip than rear that is completely predictable and throttle steerable. Its a hell of a lot faster than most liberties/sti/evos out there in the twisties simply because you arent afraid to commit a little more. Tyre pressures just play a small role in helping to sure this up.

And also to be fair, lower pressure in the front is just more comfortable. The car seems to love it. Its not exactly radical though.

[smythie]

What pressure do you run smythie?

Depends on the intended usage. But usually somewhere around 35-38