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rim width v. tire width
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Trying to figure out the right size tire for my rims, and wondering how aero factors into WRT rim width.

I have a front Zipp 808 FireCrest, which I think the rim width is 24.73 (brake track rim width). I have been running Zipp Speed Tangente tires (size 23c). I was thinking the 23c was more aero than the 25c. But now, I'm wondering if my tire is too narrow since I'm not getting the benefit of the 23c aero since my rim width (i.e., 24.73) is greater than that. So, I'm wondering if I should just use the Zipp Tangente 25c tire in the front and I won't lose any aero and gain some CRR. ???

If I had a rear disc that was not as wide (e.g., 20c), then should have have a narrower tire (e.g., 23c)? Or, maybe it doesn't matter because it's in the back shielded with all the bike fairing, etc., and I should just use the 25c (or whatever fits).
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Re: rim width v. tire width [TriFloyd] [ In reply to ]
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Firecrest wheels with wider tire beds
The best aero and lowest rolling resistance is obtained with front 23mm and rear 25mm width tires running at the recommended tire pressures.


Straight from the zipp website.

2019 T-Rex Tri Series
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Re: rim width v. tire width [mknight84] [ In reply to ]
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Maybe, that's why I was using my current setup in the first place, and I had just forgotten why i did it.
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Re: rim width v. tire width [TriFloyd] [ In reply to ]
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Also you have to remember that 23c tires mount at different widths with the same pressure depending on the rim.

Greater inner rim width creates greater outer tire width, and even rim lip design can factor in as well.

For an example I have set of 19.5mm inner / 24mm outer alloys that take a 25c Conti GP4000 at 100psi - tire width is 28mm when installed and inflated.
That same exact tire on a 17mm inner / 25mm outer carbon is 26.5mm when installed and inflated.

I believe Zipp took such findings into account when suggesting the 23mm up front, in that in general using such a sized tire will result in the flushest final mounting profile.

Of course, YMMV so to speak. Good luck with the pairing.
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