Physics question: Rims size and width
- Thread starter Gordjy
- 10 comments
- 9,762 views
- 213
- Netherlands
Ive seen cases where it affects PP, so pretty sure it will affect handling as well.
- 1,538
- NRW - GT
I tried it on my 2000 Skyline and couldn't tell any difference when changing the diameter, neither in handling nor in performance values. I was particularly hoping for improved braking performance, but nothing changed. Unfortunately, I can't make any statements about the width, I hadn't tested that. Also, I have not yet done any tests to see how wide the car changes.
I would like to do that but if I have a long time, I can catch up.
- 1,521
- Seixal
- zefthebestofcour
Sorry but could you please give us a real example on this game??? (about PP change due to this issue??)
- 1,942
- Cotswolds, UK
- doc-shipman
I haven't done any testing, but the interesting one is if you take one of the pickup trucks, slap some racing brakes on it and then go change the wheels the brakes scale with wheel size. Would be an interesting test that I may do later to see if it does actually change braking performance
- 4,020
- Wisconsin
- GTP_Eggstor
Let's test it out, at least empirically (I'm too inconsistent to do an on-track test). I grabbed a stock 2020 Toyota GR Supra and tried out the various rim sizes, widths and offsets with the standard wheel and BBS FS wheel. Here's what I found (the weight remained unchanged at 3373 lbs regardless of wheel or configuration):
It's all empirical, and only on one otherwise-unmodified car, but at least for this configuration, rim width means nothing, rim diameter on its own means nothing, the wide offset makes handling worse, and wide offset combined with a non-standard rim diameter makes handling slightly worse still (with no difference between going smaller or larger on the rim).
| Wheel | Rim Diameter | Rim Width | Offset | PP | Acceleration 0-0.25 mile | Acceleration 0-0.62 mile | Acceleration 62-93 mph | Low Speed Stability | High Speed Stability | Rotational G - 40 mph | Rotational G - 75 mph | Rotational G - 150 mph |
| Standard/BBS | 19" (Standard) | Standard | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| Standard/BBS | 19" (Standard) | Standard | Wide | 545.17 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 19" (Standard) | Wide | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 19" (Standard) | Wide | Wide | 545.17 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 18" | Standard | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 18" | Standard | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 18" | Wide | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 18" | Wide | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 20" | Standard | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 20" | Standard | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 20" | Wide | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 20" | Wide | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 21" | Standard | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 21" | Standard | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
| BBS | 21" | Wide | Standard | 545.83 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.09 | 1.11 | 1.18 |
| BBS | 21" | Wide | Wide | 545.14 | 13.65 | 23.91 | 4.47 | -0.22 | -1.00 | 1.08 | 1.11 | 1.18 |
It's all empirical, and only on one otherwise-unmodified car, but at least for this configuration, rim width means nothing, rim diameter on its own means nothing, the wide offset makes handling worse, and wide offset combined with a non-standard rim diameter makes handling slightly worse still (with no difference between going smaller or larger on the rim).
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- 670
- London
- potatoe506
Ha, I also did the exact same test myself a while back. I had the same results - edit: actually looking at it, my results were slightly different to yours -, except I don't agree with your summary on wide offset.
Aftermarket rims usually provide a higher PP value than stock rims. There are some cars (mainly race cars) where there is no difference. All aftermarket rims are equal.
Rim size does nothing even though you can see the brakes increasing in size.
Wide offset on stock wheels gives a reduction in PP. Wide offset on aftermarket wheels gives an increase in PP. Rim width does nothing.
My conclusion has been that aftermarket wheels with a wide offset is the best in terms of overall performance. Rim width and size you can do whatever with. There is definitely a noticeable difference on track, wider offset feels more 'settled' which means you should be able to get on throttle sooner and be more consistent with your lap times.
Interestingly, sometimes if you switch from stock brakes to racing brakes there is actually a very very small benefit to handling performance recorded in the PP system.
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- 4,020
- Wisconsin
- GTP_Eggstor
You probably used a different car than I did. I just redid the test using the 1969 Camaro Z28. Going to the wide track with the stock wheels (15") upped the PP from 433.01 to 434.66, with improvements in acceleration and no change in handling. Switching to the BBS wheel, adjusting the rim diameter (between 14" and 20") and adjusting the rim width between standard and wide all had no additional effect beyond the effect of changing the track between standard and wide. Again, I didn't drag the car out onto the test track, so it's all empirical.
That is why I said, "It's all empirical, and only on one otherwise-unmodified car, but at least for this configuration,...". It's fair to say that the implementation is, to put it charitably, not exactly complete.
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