View Full Version : BAR vs PSI

20-05-2015, 11:06
Wondering if anyone can help clarify this for me. I am use to working in PSI however regardless if I set the option to metric/imperial, it still shows in BAR. I ran a conversion tool to find approx values close to 32-35 PSI and I get 2.40 BAR.
This doesn't really make sense in game since I can't really set the pressure that high and where I can it is maxing out. Any help understanding the way PCars has this laid out would be appreciated.

20-05-2015, 11:09
Race cars are generally set much lower than you would a road car, simply because the tyres get much hotter, and with the increase in temperature, comes an increase in pressure.

20-05-2015, 11:12
pressure of 1 bar is really 2 bars because there's always 1 bar of atmospheric pressure. Maybe it's the cause?

20-05-2015, 11:13
pressure of 1 bar is really 2 bars because there's always 1 bar of atmospheric pressure. Maybe it's the cause?

If that was true, it would be bonkers.

I still think some of the cars max pressure is on the low side.

20-05-2015, 21:23
Race tires and slicks don't need as much pressure as a street tire. The carcass construction of a racetire supports alot more of the loads (in all directions) than a typical street carcass where it relies much more heavily on the actual air pressure for support, hence alot more of it is needed for these tires. We model all these differences in contruction of the carcass's in the SETA tire model inside Pcars. Typical race slicks run as low as 14-15lbs cold on lighter formula cars to 20-22 on the heavier GT3 type cars. Were as a street car you want more like 30-38 psi depending on the weight of the car.

20-05-2015, 22:20
Yeap Doug nailed it. I'll second that one. I've raced a lot of motorcycle on road courses and I always ran really low cold pressures with the DOT race tires or slicks compared to street radials. Like he said they don't require much pressure as the carcass is stronger. Also depending on tire brand you use the pressures will change. I usually go out to do a warm up lap and then a hot lap and then come in a quickly check my tire pressure to see if it's at the recommended hot pressure. Cold pressure usually just get you into the ball park. Not sure if PCars goes that far though and it would be nice to see a chart of recommended hot lap pressures for each car. Of course cars are much more forgiving them motorcycles.

20-05-2015, 22:24
So how do I find the equivalent in Bar? If I want to run like Doug said 14-15lbs or 20-22 or even 30PSI What would my Bar be set to?

20-05-2015, 22:25
I can never understand this bar nonsense , I'm a PSI girl

Casey Ringley
20-05-2015, 22:31
PSI = bar * 14.5

20-05-2015, 22:35
You could download a unit converter for your phone or you could also just google bar to psi https://www.google.com/search?q=bar+to+psi&oq=bar+to+psi&aqs=chrome..69i57.2219j0j8&sourceid=chrome&es_sm=122&ie=UTF-8

Basically 1 bar = 14.51 psi

21-05-2015, 00:15
Thanks for the information all. Makes sense now to see the avg Bar pressure at 140-170.

21-05-2015, 10:11
It would be great if we could also have an option for PSI rather than BAR
its not a big issue tho :)

21-05-2015, 10:42
I'd be lost without this...


21-05-2015, 12:15
I'd be lost without this...


Thanks Supaaafly!

21-05-2015, 12:41
I can never understand this bar nonsense , I'm a PSI girl

Except you're really a guy........hello XBL: Shaun Racing!

21-05-2015, 15:02
Once again:

1x BaR = 14.5 PSI (also this chart http://www.britishmetrics.com/Images/pis-bar.pdf)

Using this for your setup notes can help. It does seem harsh, but this is actually information helpful to setting up a racecar and there is absolutely no shame in using a calculator and making your own setup notebook like an engineer either (so you don't forget the bar-psi values) Or a really, really, dorky racing game player. Like me.


Jimbo Jones
21-05-2015, 19:48
Personally dont think it really matters whether youre in psi/bar mode since youre tuning for tyre temp/grip/under/oversteer, so it's just a case of+/- pressure rather than a prefered value like in Forza