Rim Size : Performance

  • Thread starter kolio
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Thanks, man. Tires are certainly new- but similar all-season compound (Falken ZX-912), and the spacers are only on the front. The biggest improvement is certainly the big reduction of sidewall, and wider wheel/contact patch -as you can see in those images. And most of my 'testing' is during normal ;) spirited driving in the twisty, country roads out in the foothills, often in the rain. Ever since I was a toddler on a plastic bigwheel, I've spent a large amount of time around the limits of grip, which gives me a decent awareness of changes and improvements. I have yet to take her to a road course, but certainly will.

And I strongly disagree when you say you've made a fool of yourself. We're all just learning things here, and to be honest I wish you would've said Tire Pressure earlier. Tire pressure vs. Trackwidth would make a great battle of worthyness! All adjustments being within reason, of course.
 
Wow some people take video games way way too serious. Your really think 90% of GT's fanbase and players would even understand any of that if it was put into the game. I think that GT6 is allowing the 1-2" wheel increase just for looks.
 
I think that's generally accepted. Instead, what I think was being discussed is whether changing wheels has a useful effect at all; "most players" (probably) don't appreciate the subtlety of upgrading a car in the game, so why don't all cars just have a "fully tuned" option?

I think you'd notice the improvement in unsprung weight in transitions and the slightly decreased flywheel effect from the reduced weight of performance wheels. The tyre model apparently takes section width into account, why not also profile (actually, there are hints that this is modeled) and offset?

It technically falls out of a proper tyre model, and suspension / drivetrain model for free anyway, might as well make it a little bit usable, if not in a full-on technical way, necessarily. You could at least make some tasty looking motors that way, too. :P
 
I went from a stock 205-55-16 tire on 6.5 in. steel wheels, to 225-45-17 tires on 8 in. wheels on my real car. I weighed the tire/wheel combo and they came out exactly the same for the 16' steelies and the 17" alloys with tires. It was something like 40.2 pounds/ corner.

The difference in overall grip is pretty clear. Both all season tires, but the new ones were "ultra-high performance" all season, so maybe a little tiny bit better compound. Then after than I put a 19mm rear anti-sway bar where there was none on the rear and again, changed the handling and feel a huge amount.

Too bad we didn't have a skid-pad in Gt6 to test out the average G between stock and +1, +2 tires/ wheel packages. That would be a pretty cool thing to have in the game. You could also test suspension mods and adjustments.
 
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Well GT6 only lets some cars get larger diameter wheels, meaning that they are getting less sidewall per wheel and depending on the size you get very little rubber and it looks kind of stupid. I will test the sizes to see if it does anything as it should make some impacts and PD doesn't let us know if the widths are changing since many wheels tend to get slightly wider when you go up in size for balance reasons so I think some cars especially economy cars that slap on bigger wheels get wider tires which should increase contact patch as perhaps slightly increase or decrease wheel weight. No idea why PD decides to leave out such vital information as well as tire pressure, I mean this game has constantly changing temperatures and weather conditions why can't we set tire pressures based on our outlook on weather by the time you get tires warmed up?

Taller wheels do impact a cars' handling, not many folks recognize that many MR super cars the front wheels are actually taller than the rears and tire to wheel ratio is lower in the front than in the rear. Some cars may have them slightly swapped but taller tires up front helps with turn in and front end grip. PD once again doesn't let us actually put their simulator to the test by letting us stagger tires based on our own driving style. So far the fix for the custom wheels is a step in the right direction but we still ability to change front and rear wheels independently(wheel size), wheel camber left and right(for Nascar).

Just for now wheel sizes aren't just for show, as the bug showed that the tires visual representation was locked into contact patch so it meant something. Lets see if we can find out what else is in there that PD doesn't out and out let us know. I really hope that GT7 really loses the adulterated approach and gets deeper and still keeps the same car encyclopedia thing GT is known for but deeper tuning, more in depth aero changes. Keep you guys posted when I find something about inch up that is concrete.
 
Has anyone done any testing?

I set a time on Apricot Hill with stock wheels, (did quite a few laps to get the best time i could)
Then i put +2's on and went 0.3secs faster on my first lap!

Whether i just did a better lap or it was the wheels i don't know, i'll have to try some more cars & tracks but anyone else have anything to add?
 
Fascinating conversation.. :)

From the few tests I've done so far, I suspect that wheel weight and the un-damped spring effect of the tyres is calculated and therefore does have an effect on car behaviour. It was an important part of the dynamics of car behaviour with the rFactor physics engine so its not a huge leap to assume GT6 has it this far down the line. I have no evidence to support this yet since I haven't had the time to run significant tests but it is on my 'to do' list and I will certainly be sharing it here. 👍
 
For this TT I had to limit rim sizes , because I noticed the performance difference between std size vs +1/+2 inch rims.

It was also not possible to enter track online if other than std size rims was fitted to stock car , with tuning prohibited on.
 

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