Tire pressure question

[Nick Hill]

So, right off the bat, this question is not necessarily AC-specific (though it certainly could apply to AC)...this just happens to be the most popular sim on RD so (in theory) I'll get the most eyeballs here.

Let me ask a very simple question (no tricks or gotchas; take this question at face value):

If you were playing a sim that hid all setup options/data from you *except* (1) the ability to see hot tire pressures and (2) the ability to adjust cold tire pressures, from a setup standpoint you would try to adjust cold tire pressures so that the L and R side hot pressures were near-sighted (i.e. front left hot tire pressure as close to front right tire pressure; same for rears).

Yes? No? Maybe? Justification?

 

[BhZ]

So, right off the bat, this question is not necessarily AC-specific (though it certainly could apply to AC)...this just happens to be the most popular sim on RD so (in theory) I'll get the most eyeballs here.

Let me ask a very simple question (no tricks or gotchas; take this question at face value):

If you were playing a sim that hid all setup options/data from you *except* (1) the ability to see hot tire pressures and (2) the ability to adjust cold tire pressures, from a setup standpoint you would try to adjust cold tire pressures so that the L and R side hot pressures were near-sighted (i.e. front left hot tire pressure as close to front right tire pressure; same for rears).

Yes? No? Maybe? Justification?

You have to adjust the pressure so that when the tyres are hot, they have the same pressure. You want the car to be balanced when it's in its working range (so hot tyres). I hope this helps, i'm not completely sure i understood your question. Feel free to ask again if my answer doesn't help.

 

[Brandon Wright]

You have to adjust the pressure so that when the tyres are hot, they have the same pressure. You want the car to be balanced when it's in its working range (so hot tyres). I hope this helps, i'm not completely sure i understood your question. Feel free to ask again if my answer doesn't help.

I'm not sure I completely understood either but that's how I would have answered. I often end up with something like 20 left front, 22 right front, 18 left rear, 20 right rear in order to get all four tires in a similar window, and it can vary from track to track depending on if it has more left or more right turns.

 

[Kek700]

I would need a "reason" rather than just doing it.

 

[BhZ]

I would need a "reason" rather than just doing it.

The reason is there. The car needs to be balanced and there's no point in having a tyre with a non-perfect pressure when it's in its working range. You always have to consider a race situation: so tyres at around 90 degrees, check the pressure and change it if it's not in its working range.

 

[Peter Stefani]

Sort of off topic, but How do you adjust tire pressures when entering the pit box in a on-line lobby? I see the "box" with all the stuff to do, but I don't see TP adjust? Any idea? THX

 

[Kek700]

True, but quite often the tyres are not in a perfect temp range, and quite often they are not at the same pressure for every braking point on the circuit.

 

[Peter Stefani]

The only work-around I see is to pull out of the "box", then Menu select Pits, then select set up and adjust TP's. Seems like a time consuming effort. Is there any other way???

 

[Brandon Wright]

I would need a "reason" rather than just doing it.

The reason is you want all four of your tires in the ideal pressure range, and due to differing car and track geometries they're rarely going to be the same on all four corners or from one track to the next. On a track with a lot of left hand turns you're going to need higher pressures on the left side, and vice versa for a track with more right hand turns than left. I use the Sidekick mod app, it shows in real time if your pressures are in the ideal range and tells you how much you need to increase/decrease pressure on each corner. Works a treat and the results are great. Sure the pressures vary a little around a lap but as long as they're +/- 1psi from ideal you're good to go. I don't even pay attention to temperatures anymore, I find as long as you have the pressures right the temps work themselves out.

Sort of off topic, but How do you adjust tire pressures when entering the pit box in a on-line lobby? I see the "box" with all the stuff to do, but I don't see TP adjust? Any idea? THX

It's best to setup a pit strategy from the setup screen first. Then during the race when you want to pit hit your d-pad on the wheel and it will bring up the pit menu box, select your strategy, drive into the pits, good to go. I believe you can also adjust the settings on the fly once you pull up the pit menu box but it's kinda hard to do while driving.

 

[BhZ]

I use the Sidekick mod app

You sure you meant sidekick and not protyres? Sidekick shows the tyre usage % and brake temp (if supported by the car) but i don't think it shows the pressure of the tyres.

 

[Peter Stefani]

It's best to setup a pit strategy from the setup screen first. Then during the race when you want to pit hit your d-pad on the wheel and it will bring up the pit menu box, select your strategy, drive into the pits, good to go. I believe you can also adjust the settings on the fly once you pull up the pit menu box but it's kinda hard to do while driving.[/QUOTE]
Thanks for the reply, maybe I did not see the "pit Strategy" in the set up screen. (console user) But I will look again.

 

[Brandon Wright]

You sure you meant sidekick and not protyres? Sidekick shows the tyre usage % and brake temp (if supported by the car) but i don't think it shows the pressure of the tyres.

Yes, Sidekick. It has several options and one of them shows you how to adjust your pressures to get them in the green. It's very handy, I don't think it shows what the actual pressures are but it shows you how much to increase/decrease pressure on each tire to get it in the ideal range.

Thanks for the reply, maybe I did not see the "pit Strategy" in the set up screen. (console user) But I will look again.

Oh. I'm not sure how it works on consoles but that's how it works on PC. When you're out on track try hitting the d-pad (any direction) and see if it pops up the pit options menu on the right side of the screen. If it does then you can make your adjustments through there, I believe tire pressures are one of the options you can adjust.

 

[Nick Hill]

Thanks for all the feedback, gents! This is exactly what I was looking for confirmation on.

In my mind, if you aren't going to take the time to make sure you've set cold pressures that are giving you more or less equal hot temps, you might as well not bother with any other more sophisticated suspension setup tweaks.

Hypothetical example based on my understanding:

- Counter clockwise track (more lefts than rights)
- "Ideal" tire pressure for my car = 20 psi (all 4 tires)
- Cold tire pressures for my car = 16 psi (all 4 tires)
- After getting to the point where I can turn consistent, fast-ish laps, I observe:
> Left side tires running at around 18 psi
> Right side tires running at around 22 psi
> Car is exhibiting handling quirks (for the sake of this argument, it doesn't really matter what - fill in whatever you want: understeer, oversteer, on power, on coast, etc, etc)

My whole point is, based on my current understanding, it would be a far more effective setup approach in terms of results and time spent to begin with addressing the fact that my hot pressures are 2 psi too low on the lefts and 2 psi too high on the right before I start messing around trying to fix <insert observed handling quirk here>.

In essence, if you're running around with tire pressures that haven't been corrected for the particular track conditions, then you frankly don't truly know what the cars "handling quirks" may or may not be. Fix the pressures and the original quirk may disappear...or get worse...or completely flip (e.g. go from understeer to oversteer, etc).

At least, this is how I've come to approach things. With my question, I was really seeking to find out if others share this mindset or if I am being overly simplistic.

In my anecdotal experience, I often find that adjusting the tire pressures is literally the only setup tweak I need to make (other than obvious stuff like gear ratios, wheel lock, etc). I am a little frustrated with myself over all the time I've spent over the last few years trying to understand how, in someone else's setup they've shared with me, they knew to go from a 3 to a 4 on the front damper's slow rebound setting. Please note that I'm not dismissing those types of setup changes outright - I really believe there are people with a combination of a refined enough feel for the car plus sufficient physics/engineering knowledge to benefit from such tweaks...I have just personally come around to the understanding that I'm not currently (and may never be) one of them.

 

[Brandon Wright]

Hypothetical example based on my understanding:

- Counter clockwise track (more lefts than rights)
- "Ideal" tire pressure for my car = 20 psi (all 4 tires)
- Cold tire pressures for my car = 16 psi (all 4 tires)
- After getting to the point where I can turn consistent, fast-ish laps, I observe:
> Left side tires running at around 18 psi
> Right side tires running at around 22 psi
> Car is exhibiting handling quirks (for the sake of this argument, it doesn't really matter what - fill in whatever you want: understeer, oversteer, on power, on coast, etc, etc)

My whole point is, based on my current understanding, it would be a far more effective setup approach in terms of results and time spent to begin with addressing the fact that my hot pressures are 2 psi too low on the lefts and 2 psi too high on the right before I start messing around trying to fix <insert observed handling quirk here>.

Yep. But in my experience you'll rarely have the same pressures on any two tires. On a counter clockwise track the left side will need to be higher than the right side but the front left will likely be different than the rear left, so I usually have a different value on each corner based on what the track calls for. But the basis of your premise is correct, having the same pressure on all four corners is rarely the best way to go (in my experience), you need to add/remove pressure to one side based on whether the circuit has more lefts or more rights.

 

[Nick Hill]

Yep. But in my experience you'll rarely have the same pressures on any two tires. On a counter clockwise track the left side will need to be higher than the right side but the front left will likely be different than the rear left, so I usually have a different value on each corner based on what the track calls for. But the basis of your premise is correct, having the same pressure on all four corners is rarely the best way to go (in my experience), you need to add/remove pressure to one side based on whether the circuit has more lefts or more rights.

Yes, but just to be clear though, when you say "you'll rarely have the same pressures on any two tires", I might want that statement amended to "you'll rarely have the same cold pressures on any two tires" - would you agree?

The cold pressures really only matter in the sense that they will be a key input in the function that determines the eventual hot pressures.

 

[Brandon Wright]

Yes, but just to be clear though, when you say "you'll rarely have the same pressures on any two tires", I might want that statement amended to "you'll rarely have the same cold pressures on any two tires" - would you agree?

The cold pressures really only matter in the sense that they will be a key input in the function that determines the eventual hot pressures.

Probably. Whatever the numbers are in the setup screen is what I was referring to. I never have any idea what my actual pressures are when I'm driving and the tires are hot, I just know if they're in the ideal range or not based on what color is being displayed in Sidekick.