Rim Size : Performance

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Wheel width and offset have an astounding effect on the lateral grip of your vehicle. Wheel diameter and tire profile are secondary to these first two.

Also adding aftermarket lightweight wheels over some heavy stockers will yield HUGE performance gains in accelleration, braking, handling (all three!) due to the reduced unsprung rotational weight- the best kind of weight reduction money can buy.



Johnnypenso
... they better take it into consideration in PP levels otherwise everybody in open lobbies will have the fattest tires possible on every car:lol:
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well you reach a point where bigger/fatter starts increasing the unsprung weight. This can get quite detrimental in a hurry. Of course we're assuming the weight of wheels/tires is being modelled, as it definitely should..
 
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Wait, i thought its only increasing the Rim size i didn't know it also increases width.

Tyre Width upgrades give a significant performance increase.
 
I don't think using different size rims should affect the games performance. The model is the same just scaled up.
 
dmcallis
I just hope you can mix sizes front and rear (bigger on rear...) Many cars would benefit from this. If they model contact patch it will make a difference... I can't see Yokohama not impressing this fact upon PD. It's mostly about the contact patch and weight transfer... (yes, I know tire flex and such is where bigger rims and lower-profile tires is largely concerned. This should be in the model also.)
Yokohama would talk contact patch and sidewall flex, K&W would talk weight transfer... Together, we should get a good representation of real life handling, if PD did their job properly in the programming of a proper model.
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Take a look at the premium GT500 cars in GT5. You might be able to see that the rear wheels are smaller than the front. There is a bigger tire sidewall as well. Irl, GT500 run 18" front 17" rear wheels. They have outstanding tire grip and a reason they have great traction without traction control is they can run different tire pressures and get away with low settings because there is more 'tire' in the rear.
 
I believe rim-size is just for appearance in GT6. Unless they include the various weights of the rims there is no way to calculate rotational mass and implement how it affects acceleration. The same could be said for tire width affecting how much traction the car will have. I doubt they developed a working physics engine to include those factors, but let's see on December 6th, shall we?
 
Steph290
I believe rim-size is just for appearance in GT6. Unless they include the various weights of the rims there is no way to calculate rotational mass and implement how it affects acceleration. The same could be said for tire width affecting how much traction the car will have. I doubt they developed a working physics engine to include those factors, but let's see on December 6th, shall we?
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Incorrect, Wheel width is factored into the PP equation which means the physics has factored it in, and you can tell on many of the older cars when you put racing tyres on them they still suffer from rear grip due to thin tyres.
 
mustafur
Incorrect, Wheel width is factored into the PP equation which means the physics has factored it in, and you can tell on many of the older cars when you put racing tyres on them they still suffer from rear grip due to thin tyres.
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Wheel width is factored in the pp equation? Could you please tell me where that information is proven? Not that it might not be true, but there's no reason to say that they just didn't give each car a base traction level.
 
Here's hoping rim size affects performance; it'd seem pretty daft for it not to. Then again, the aftermarket rims in GT5 had pretty much no effect on performance: there's talk of a few thousandths per 1/4 mile in the drag section, but only with certain cars, so pardon my skepticism. If each wheel's weight is different, and that's further affected by the rim size, then we're talking!
 
Applying bigger diameter and wider wheels to most cars can adversely affect the cars performance.Usually by making it feel slower on acceleration because of the added weight.In some instances wider wheel/tyre combos can help with cornering speedand make it "feel" like it actually handles better.

In my experience,changing to a larger wheel/tyre combo almost never gives a street car a worthwhile advantage.
Car Companies don't spend millions of dollars on research and development on the ideal combo for some "chump" to come along and throw it out the window.

I often laugh when I see an older vehicle with a +3 or 4 fitment and I bet the driver wonders why the car feels like it's lost 50-80hp.
 
The only time you want a Bigger Wheel diameter Performance wise, is if your current one is Tiny and there is minimal tyre wall rigidity because of it, and or your upgrading the brakes and the wheel size has to be increased to fit them.
 
I don't expect rim size to affect performance in GT6, and honestly that doesn't bother me whatsoever.

I don't think PD should be implementing features that make it detrimental to visually customise your vehicle, especially when there's shortcomings within the tuning menus that are completely ignored anyway.

Case in point - weight reduction not resulting in any of the car interiors being removed. If you can suspend reality for that, you can suspend reality for aftermarket rims.
 
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Eyes Fried Open
The width of rubber makes a big difference, this is the only point of contact your car has with the road. To say "I don't think it's going to make that much of a difference to be honest" & "something as small as this" you must be taking the mickey mate.
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If we're only allowed to "up 1" when it comes to wheels with likely no tire size control in gt6, the difference will likely negligible.
research
Also adding aftermarket lightweight wheels over some heavy stockers will yield HUGE performance gains in accelleration, braking, handling (all three!) due to the reduced unsprung rotational weight- the best kind of weight reduction money can buy.
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What's your definition of huge?
 
I think in GT6 the main performance gain we will see will remain to be type of tyres chosen.

As far as rim width and diameter they should only highlight the cosmetic side of this and wait for PS4 GT7 to code performance enhancements associated with those changes.
 
]If we're only allowed to "up 1" when it comes to wheels with likely no tire size control in gt6, the difference will likely negligible.


What's your definition of huge?[/quote]

A one pound gain in each wheel (driven or not) is like taking a racing flywheel mod and putting on the original flywheel. BIG loss in power!
 
I can't see all the extra factors that changing the wheel & tyre size bring being included. In addition to the contact patch differences caused by width, sidewall lean etc you also need to factor in pressure and tyre flex (smaller rims with bigger tyres soak up lots more bumps meaning suspension can be set much harder like in F1 etc). There is far too many variables to think that it could be in a PS3 game,
 
mustafur
Incorrect, Wheel width is factored into the PP equation which means the physics has factored it in, and you can tell on many of the older cars when you put racing tyres on them they still suffer from rear grip due to thin tyres.
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Is that true? If yes, thats awesome. Man, PDs PP system is full of mysteries xD Is there any thread to discuss PP? Besides HP/weight/aero, we also have tire width and weight balance affecting it.
 
TRLWNC7396
A one pound gain in each wheel (driven or not) is like taking a racing flywheel mod and putting on the original flywheel. BIG loss in power!
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The difference of 1lb is nowhere near as big as you think.
 
eSZee
The difference of 1lb is nowhere near as big as you think.
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That may be, but it still does make a difference. More mass equals more power to get it rolling, stopping, etc. And when you have 4 lbs, it adds up quickly.
 
Increasing rotating masses will increase the car's inertia, not cause the engine to lose power.
By the way, increasing flywheel weight has a much larger effect on performance than heavier wheels, especially at lower gears (if the flywheel was heavy enough, and I mean *really* heavy, the car would for example accelerate faster in second gear than in first gear).
 
research
Wheel width and offset have an astounding effect on the lateral grip of your vehicle. Wheel diameter and tire profile are secondary to these first two.
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How does offset affect lateral grip? All you're doing is shifting your track. Your diameter probably does not make as much difference in grip either, your contact patch may vary but it would be close to negligible and hard enough to model.

TRLWNC7396
That may be, but it still does make a difference. More mass equals more power to get it rolling, stopping, etc. And when you have 4 lbs, it adds up quickly.
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Well when your car is made to be light (ie. a race car) that's true. When your car is made to a certain level of luxury (ie. a road car) it's not gonna make any difference.
 
shirakawaa
Bigger rims = heavier wheels = lower straight-line performance. I hope this is well rendered.
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Wait what? Replacing heavy manufacturer oe 15 inch rims with 16 inch wider lightweight rims is likely to save weight, add grip and reduce unsprung weight. ..
 
Mr P510
In my experience,changing to a larger wheel/tyre combo almost never gives a street car a worthwhile advantage.
Car Companies don't spend millions of dollars on research and development on the ideal combo for some "chump" to come along and throw it out the window.
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Larger overall diameter, no. But if you have less sidewall due to a larger wheel with thinner tires, that will make a difference.

Whether it's positive or negative largely depends on how good or bad the stock tires are. Many mass market cars come with very tall tires, which are not great in transitions and are not stable in cornering... not that GT5 actually cares about wiggly tires at all. It assumes all tires have infinitely stiff sidewalls. :D (Put enough pressure in them.... hmmm.)

Car companies spend millions of dollars on research and development to come up with a road car that's an acceptable compromise between performance, cost, comfort and longevity. Not one that is as fast as possible around a racetrack

And then after spending those millions of dollars, for the "sporting" version of the same car, they go and do the same thing us enthusiasts do. Got a chuckle when reading through the press kit for the Jaguar XFR-S. The gave it bespoke 20" wheels that were half-an-inch wider than stock. Good way to get more performance out of the rubber, stretching and stiffening the sidewalls like that. ;)

That kind of very subtle, very effective change would be wonderful if implemented in a videogame.
 
shirakawaa
Increasing rotating masses will increase the car's inertia, not cause the engine to lose power.
By the way, increasing flywheel weight has a much larger effect on performance than heavier wheels, especially at lower gears (if the flywheel was heavy enough, and I mean *really* heavy, the car would for example accelerate faster in second gear than in first gear).
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This isn't aimed at you since you seem to understand it, but what's important to realise is that it's not just the difference in weight (mass), in terms of the overall weight of the car, that matters - because the wheels rotate, you have to get them spinning as well as moving across the ground.

That means there are two "sinks" for energy in the wheels, whereas most of the car has only one (translational movement). The energy for that comes from the engine, of course, and the power dictates how quickly that energy can be provided. So if some of that energy must be put into moving and spinning heavier (or lighter) wheels, then it will result in less (or more) power "left over" to get the car itself moving.

Obviously, that's not mechanically what's going on, but the energy is still shared and it is delivered to the wheels first, then to the car through the suspension via a reaction force (which produces an acceleration).

See here for the physics, sort of. What's important to note in addition is that with two wheels that weigh the same, but one is larger than the other, the larger one will slow the car down more because its mass-moment of inertia is greater, thanks to having much of its weight further from the centre of rotation than in the smaller one.
For example: a 29" bicycle wheel's rim is 25% more rotationally "inert" than a 26" of the same mass (distribution), which is 17% more inert than a 24", which is 44% more inert than a 20" (which in reality would weigh much less and be more rigid, too).


For suspension kinematics, the rotational motion imparted on the wheel through suspension travel is relatively small, but the arcs are relatively large in radius - this means that moments of inertia are still important, and so is mass and size of the wheel. There is a similar effect with steering geometry, and much of that contributes / colours the "feel".

All of this is compounded with / played off against any changes in the tyres, so it should be plainly obvious that this is a large playground with plenty of room for experimentation, preference and confusion! :p
 
That said (and I hope you didn't blow too many brains with that post! :lol: ), it's interesting to note that manufacturers are now looking at very light, very tall, large diameter wheels and tires to go with their new eco-cars.

Bridgestone is putting into production tires such as on the VW XL1, which look more like bicycle tires than car tires. Now if you could put those on a Ferrari in-game... imagine all the fun we could have...
 
niky
That said (and I hope you didn't blow too many brains with that post! :lol: ), it's interesting to note that manufacturers are now looking at very light, very tall, large diameter wheels and tires to go with their new eco-cars.

Bridgestone is putting into production tires such as on the VW XL1, which look more like bicycle tires than car tires. Now if you could put those on a Ferrari in-game... imagine all the fun we could have...
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Just to add to that.
Watching some video coverage from this years SEMA there are quite a few companies manufacturing full Carbon wheels...maybe you can have the best of both worlds...IF,you can afford it.
 
ShiftingGears
I don't think PD should be implementing features that make it detrimental to visually customise your vehicle, especially when there's shortcomings within the tuning menus that are completely ignored anyway.
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Why not? It's claimed to be a "simulator" so why shouldn't we have things that reinforce that title?

Tire size/width is a big part of motorsport in real life. It almost seems stupid not to have such a feature implemented.
 
Now in real life, rims make a difference. Some are heavier, some lighter. The offset changes the centers of the tires. The width of tires than can be put on. Larger diameter rims will have tires with smaller profiles if they maintain the same outer diameter.

However...

I have never heard of this being a play factor in any version of Gran Turismo. If I'm wrong, I'd sure like to know!
 

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