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Old 04-14-2017, 06:56 AM   #1
Chris1529
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Default Bias vs Radial slick

I have 28 x 9 M/T Bias slicks on my car right now. If I switch to a 28" Radial, can I expect much finish line RPM difference? Anyone have any finish line RPM info they can share when switching from Bias to Radial on the same size advertised tire on?
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Last edited by Chris1529; 04-14-2017 at 06:59 AM.
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Old 05-07-2017, 11:15 PM   #2
LemonWedge
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Default Re: Bias vs Radial slick

The 28x9 MT ET Drags measure 27-1/2" according to MT. Depending on how fast you are, it likely grows to 28" or even a little beyond. A radial won't grow. So if the radial you're looking at is exactly 28", you likely won't see much change in stripe RPM.

The key here is that bias tires grow while radials do not.
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Old 05-12-2017, 08:53 PM   #3
Mike Rietow
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Default Re: Bias vs Radial slick

Quote:
Originally Posted by Chris1529 View Post
I have 28 x 9 M/T Bias slicks on my car right now. If I switch to a 28" Radial, can I expect much finish line RPM difference? Anyone have any finish line RPM info they can share when switching from Bias to Radial on the same size advertised tire on?
The bias has high energy losses at all frequencies (deformation). The Radial will have low energy loss at low frequency which means less resistance to roll. Less rolling resistance means more mph. More mph requires more rpm. How much more rpm? ... How much more mph?
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Old 08-13-2018, 11:45 PM   #4
LemonWedge
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Default Re: Bias vs Radial slick

I just went from an MT 28x9 ET Drag slick to a 28x9 Pro Bracket Radial. Iíve only made a couple of passes, so results are purely preliminary; but it would appear I picked up roughly 1 mph and perhaps as much as a tenth. Didnít notice any real change in stripe RPM, but I only had 1 hit then dial.... 1st round I chopped a couple at the stripe, so the jury is still out. My sense is no real change in effective gearing.

Iíll check back in here after I have some reliable data.
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Old 08-15-2018, 09:27 AM   #5
Chris1529
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Default Re: Bias vs Radial slick

Thanks for the info. I haven't purchased any new 28" tires yet to try.
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Old 08-30-2018, 11:18 PM   #6
LemonWedge
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Default Re: Bias vs Radial slick

Iíve got more than a handful of passes on them now. Maybe 200 RPM increase at the stripe. Iím very happy with the initial results Iíve seen from these PBRís.
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