GT7 Tuning Calculator - Download V2.01 with Dyno plot built in!

Just a quick question, I’m sure it’s been answered already but I’m late to the show, took a break from the game. How do we install updates when they are made to your excel? I am a lite user. Great tool, it helps a lot for a returning player 😊
 
Lochstina
Just a quick question, I’m sure it’s been answered already but I’m late to the show, took a break from the game. How do we install updates when they are made to your excel? I am a lite user. Great tool, it helps a lot for a returning player 😊
Click to expand...
As soon as an update is released you will receive an email from Shopify with the new file download link.
 
Hi,


I'm really happy with your tuning calculator. It takes away the guessing game and a lot of frustration!

I wanted to add that changing the wheel diameter in-game does not change the outside diameter of the wheel. Your gear ratio changes with changing the diameter, but it shouldn't, it would be a good trick to get the gears in the correct range, I suppose.

With changing the wheel diameter, you visually change the height of the tyre wall and the size of you racing discs. On track idk if the discs have any effect, but the changed tyre wall height does. The compression and decompression gets simulated in-game and affects suspension settings. Before having your sheet it was really difficult to find a good balanced setup to perform. Playing with the tyre size and track settings was a big part of my base setup. Thicker tyre walls compensate for a lack of perfect suspension settings.

I have a question about the stability score and rotational G you get when changing parts. With the AMG GT R, stability is all over the place when you change the anti-lag/flywheel options between themselves, in some instances the carbon shaft too and I don't know what to pick as a base. It's very buggy and affects the settings in the calculator.

edit: The AMG GT R's rotational G is higher without rear spoiler than with it, should I leave it off then?
 
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Daxus
Hi,


I'm really happy with your tuning calculator. It takes away the guessing game and a lot of frustration!

I wanted to add that changing the wheel diameter in-game does not change the outside diameter of the wheel. Your gear ratio changes with changing the diameter, but it shouldn't, it would be a good trick to get the gears in the correct range, I suppose.

With changing the wheel diameter, you visually change the height of the tyre wall and the size of you racing discs. On track idk if the discs have any effect, but the changed tyre wall height does. The compression and decompression gets simulated in-game and affects suspension settings. Before having your sheet it was really difficult to find a good balanced setup to perform. Playing with the tyre size and track settings was a big part of my base setup. Thicker tyre walls compensate for a lack of perfect suspension settings.

I have a question about the stability score and rotational G you get when changing parts. With the AMG GT R, stability is all over the place when you change the anti-lag/flywheel options between themselves, in some instances the carbon shaft too and I don't know what to pick as a base. It's very buggy and affects the settings in the calculator.
Click to expand...
Hi Daxus,

Great to hear your having success with the calculator!

Have you done any testing of the wheel/tyre size? From what I have tested the top speed changes with wheel size and also bottoming out can occur if large wheels are fitted and the ride height is too low... Let me know your test results if you have found otherwise.

I know what you mean in terms of the stability and G force figures, they are very buggy. random part changes complete change the stability figures and I have not worked out why yet. I have found that to get a car to handle better you want to have the stability at low speed as close to neutral as possible, I tend to look for a figure between -0.30 and 0.00 depending on the car. Use ballast and weight distribution to get the optimum stability...

Phil
 
hookedonturbo
Hi Daxus,

Great to hear your having success with the calculator!

Have you done any testing of the wheel/tyre size? From what I have tested the top speed changes with wheel size and also bottoming out can occur if large wheels are fitted and the ride height is too low... Let me know your test results if you have found otherwise.

I know what you mean in terms of the stability and G force figures, they are very buggy. random part changes complete change the stability figures and I have not worked out why yet. I have found that to get a car to handle better you want to have the stability at low speed as close to neutral as possible, I tend to look for a figure between -0.30 and 0.00 depending on the car. Use ballast and weight distribution to get the optimum stability...

Phil
Click to expand...
I've tested the tyre sizes vs speed in the very beginning, but I'll try again. You can visually see the changes in GT Auto and hold a finger on your screen to the outside diameter when you change tyres, but with this game's bugs you never know.

I've always supposed the wheel lock was from too soft springs vs downforce and speed or just too low. Together with that bottoming out should be worse when you put on smaller wheels.
The stability must be a math rounding error inside GT7's pp-calculation or something, some cars you see drop/drop/dop/raise/drop... in a fairly repeating pattern. I understand what you say about the adding weight, but I'll post my video to show that AMG is very extremely bugged.



But really that calculator is awesome :D
 
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Can anyone else confirm or deny that wheel sizes change the size of the overall tyre diameter? @bread82 have you done any research to seen anything to do with this?
 
Daxus
I've tested the tyre sizes vs speed in the very beginning, but I'll try again. You can visually see the changes in GT Auto and hold a finger on your screen to the outside diameter when you change tyres, but with this game's bugs you never know.

I've always supposed the wheel lock was from too soft springs vs downforce and speed or just too low. Together with that bottoming out should be worse when you put on smaller wheels.
The stability must be a math rounding error inside GT7's pp-calculation or something, some cars you see drop/drop/dop/raise/drop... in a fairly repeating pattern. I understand what you say about the adding weight, but I'll post my video to show that AMG is very extremely bugged.



But really that calculator is awesome :D
Click to expand...

Please teat again and let me know, I am away form the console for now.
 
Abarth_71
As far as I know fitting a larger diameter wheel just means a lower profile tyre, so the overall size remains the same.
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As far as you know? Have you tested the theory or just going off of the visuals in gt auto? I’m just not certain that these visuals are accurate.
 
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hookedonturbo
Can anyone else confirm or deny that wheel sizes change the size of the overall tyre diameter? @bread82 have you done any research to seen anything to do with this?
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I've tested it again



I started with the biggest wheels and mounted the smallest afterwards. With an easy to top out gearing I get exactly the same speed with the slight difference that it seems to struggle a bit sooner to get there on the smaller size tyre.
 
hookedonturbo
As far as you know? Have you tested the theory or just going off of the visuals in gt auto? I’m just not certain that these visuals are accurate.
Click to expand...
Not from the visuals, just makes sense to me that if you fit bigger wheels you'd keep the same overall diameter with a lower profile tyre. They also provide better traction which may explain the difference in acceleration in the above post.
 
Daxus
I've tested it again



I started with the biggest wheels and mounted the smallest afterwards. With an easy to top out gearing I get exactly the same speed with the slight difference that it seems to struggle a bit sooner to get there on the smaller size tyre.
Click to expand...

hmm Okay, Looks like you are right. Not sure what we are going to base the wheel size on now... generic 25"/637.5mm?? Should work for most. cars just not the small cars. this is right spanner in the works...
 
hookedonturbo
hmm Okay, Looks like you are right. Not sure what we are going to base the wheel size on now... generic 25"/637.5mm?? Should work for most. cars just not the small cars. this is right spanner in the works...
Click to expand...
You could keep the function and change the name to gearing tweaker or something with the correct value for every car, I guess it could be useful for people who get out of bound results.

edit: To know the true value you could physically measure the difference in diameter from the screen, the true tyre size diameter is usually where the tyre meets the rim, so just below the outside diameter of the rim itself.
 
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Daxus
You could keep the function and change the name to gearing tweaker or something with the correct value for every car, I guess it could be useful for people who get out of bound results.

edit: To know the true value you could physically measure the difference in diameter from the screen, the true tyre size diameter is usually where the tyre meets the rim, so just below the outside diameter of the rim itself.
Click to expand...
Right okay, I think we can just continue to use this. it must be based on the standard wheel size (plus tyre height)…
 
I'll check when I'm on GT7 later but I think the overall dia is constant, it was in previous GTs anyway. Basically if the car holds the same speed for the same gear and revs, before and after wheel swap, the tyre diameter is unchanged. Daxus' video has shown this.

Total tire size can be back calculated from road speed, gear ratio, final drive, and engine rpm.

Eg (made up example) if you're doing 200 kph, engine is at 6000 rpm, in top gear of 0.8 ratio, through a FD of 4.0.

Wheel revs = 6000 / 0.8 / 4.0 = 1875 rpm wheel.

Wheel revs per hour = 1875 * 60 = 112,500 rph

road speed metres ph/wheel rph = 200,000 / 112,500 = 1.78 metres circumference of tyre.

Divide 1.78 m by pi gives 0.57 m dia, which is 22.4 inches.

So if the game does all this off a 17 inch alloy then you know there's 22.4-17 = 5.4 inch of rubber or 2.7 inch on each side of the wheel.

Also with the total tyre dia being 0.57 m in my example, that's 0.285 m radius which is your effective lever length for turning the axle torque into tractive force on the road, which is helpful to know for your other calcs.

The PP changes with wheel size, so I'd expect some grip differences (due to sidewall stiffness) and/or rotational inertia differences. Daxus said it felt different on the smaller tyres which makes sense.

Alloys don't show a reduced car weight in GT7, but ddm said in the special parts thread that the carbon prop shaft changes propellor and wheel rotational inertia properties so it looks like these things are modelled. Maybe the wheel size changes the inertia too.

A difference in the quarter mile stats could confirm this, if it updates them (albeit if the tyre grip changes too, you'll never know which effect, grip or rot inertia, was responsible).

Edit: you could have input cells in your sheet for engine rpm, gear ratio, FD, speed etc and have it spit out the tyre dia.

But it's important for the user to do a max speed run like Daxus demonstrated. Big speed gives more precision and also the car should be at steady state flat speed, not accelerating, since wheel slip under accel will skew the results (because GT's Speedo isn't driven by gearbox speed like IRL, it's more of a GPS true speed).
 
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bread82
I'll check when I'm on GT7 later but I think the overall dia is constant, it was in previous GTs anyway. Basically if the car holds the same speed for the same gear and revs, before and after wheel swap, the tyre diameter is unchanged. Daxus' video has shown this.

Total tire size can be back calculated from road speed, gear ratio, final drive, and engine rpm.

Eg (made up example) if you're doing 200 kph, engine is at 6000 rpm, in top gear of 0.8 ratio, through a FD of 4.0.

Wheel revs = 6000 / 0.8 / 4.0 = 1875 rpm wheel.

Wheel revs per hour = 1875 * 60 = 112,500 rph

road speed metres ph/wheel rph = 200,000 / 112,500 = 1.78 metres circumference of tyre.

Divide 1.78 m by pi gives 0.57 m dia, which is 22.4 inches.

So if the game does all this off a 17 inch alloy then you know there's 22.4-17 = 5.4 inch of rubber or 2.7 inch on each side of the wheel.

Also with the total tyre dia being 0.57 m in my example, that's 0.285 m radius which is your effective lever length for turning the axle torque into tractive force on the road, which is helpful to know for your other calcs.

The PP changes with wheel size, so I'd expect some grip differences (due to sidewall stiffness) and/or rotational inertia differences. Daxus said it felt different on the smaller tyres which makes sense.

Alloys don't show a reduced car weight in GT7, but ddm said in the special parts thread that the carbon prop shaft changes propellor and wheel rotational inertia properties so it looks like these things are modelled. Maybe the wheel size changes the inertia too.

A difference in the quarter mile stats could confirm this, if it updates them (albeit if the tyre grip changes too, you'll never know which effect, grip or rot inertia, was responsible).
Click to expand...
I find it bizzare that they go to a lot of effort modelling aerodynamics and inertia etc, but tyre diameters are the same whether it’s a 16 inch wheel or an 18 inch wheel.
Hey Ho, thats PD for you lol.
 
Ok so, after a bit of testing and confirming that the tyre diameter does not change with the wheel size I have made the following tweak to the calculator.

Replaced the Wheel Size input with standard wheel size.

Changed the Gear ratio calculation so that tyres on Road and GR4 cars are 35% rubber on top of the rim diameter, Race cars have 55% tyre over the rim size.

should give us more accurate top speeds inline with the calculator Input.

I will update the new version at some point today.
 
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hookedonturbo
Can anyone else confirm or deny that wheel sizes change the size of the overall tyre diameter? @bread82 have you done any research to seen anything to do with this?
Click to expand...
I know that PP changes with a wider wheel offset and stance, possibly with a larger rim. We're talking less than 1 PP, but it does affect the physics. Same with a roll cage, maybe 1 PP. As does widebody, but there it's often 3, 5 PP, or more.
 
willydotcom
I know that PP changes with a wider wheel offset and stance, possibly with a larger rim. We're talking less than 1 PP, but it does affect the physics. Same with a roll cage, maybe 1 PP. As does widebody, but there it's often 3, 5 PP, or more.
Click to expand...
I think I know, that only the wheel size and the offset change the PP.

I'm pretty sure, that a wider wheel won’t change the PP.
 
Some more strangeness with spring values after the latest update.

The spring rate for some race cars vary wildly between the Expert and Lite versions (particularly Gr.B cars and unclassed oddballs like the Escudo and the BRZ Drift Car).

Expert Version:
1685608802508.png


Lite Version:
1685608777858.png


With the same inputs, all output values are identical except for Spring Rate.

The latest Expert calculator matches the output of the previous versions, so I would assume it's the Lite calculator that's off?
 
Techlet
Some more strangeness with spring values after the latest update.

The spring rate for some race cars vary wildly between the Expert and Lite versions (particularly Gr.B cars and unclassed oddballs like the Escudo and the BRZ Drift Car).

Expert Version:
View attachment 1261470

Lite Version:
View attachment 1261469

With the same inputs, all output values are identical except for Spring Rate.

The latest Expert calculator matches the output of the previous versions, so I would assume it's the Lite calculator that's off?
Click to expand...
Oooo, what have I missed there? I’ll get resolved now.
 
What does everyone think of the new version? Had a chance to test out the new ARB stiffness and over/under steer toggle?
 

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