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Maximum tire size % difference to trigger ABS??

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Old 03-12-2011, 04:23 PM
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Default Maximum tire size % difference to trigger ABS??

Guys, according to a tire size calculator, the percentage difference between my two tires is 2.7%

can this much difference trigger ABS under moderate/hard braking?

tires are 245/40/18 front and 305/35/18 rear

i used to run same fronts but with 275/35/18 rears which is only a 0.5% difference, and I feel like now with the 305's, the ABS is coming in a lot sooner.
Old 03-12-2011, 08:18 PM
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I run the same sizes front and rear. With the ABS operational, I would get ABS activation even during moderate braking. And after a steady cruise of 55-60mph the system would detect the wheel speed differential and shut down.
Old 03-13-2011, 07:58 PM
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Originally Posted by Marc 85Z28
I run the same sizes front and rear. With the ABS operational, I would get ABS activation even during moderate braking. And after a steady cruise of 55-60mph the system would detect the wheel speed differential and shut down.
im not sure what you mean by "shut down"
Old 03-13-2011, 08:09 PM
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can this be reprogrammed?
Old 03-13-2011, 10:19 PM
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About 1" difference and ABS will let you know the variance is great enough to turn a code.

What you may not realize is that when you're using different diameter tires with ABS or TCS, even it it is only a "small" difference, the difference will throw functionality off.

Think of it this way, say you take a cam that is slightly modified...then engine will run but is not correctly configured for the stock computer. The stock computer response on programming of a stock cam, not a modified cam. Same situation when you vary the tire diameters...the computer bases its response on tires that are equal size, not different.

What does this mean...well ABS and or TCS will probably activate at times when you DON'T want it to...and will work against you creating worse braking response and or traction control. ...in an nutshell, if you rely on ABS/TCS and feel warm and fuzzy about how it can help you...don't expect the same response with varied tire diameters.

No aftermarket programing is available for the F-body ABS system. An option and work-around is to consider removing ABS and TCS using one of our ABS delete kits...where you can tune brake bias using the adjustable proportioning valve included with our kits.
Old 03-14-2011, 08:03 AM
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Originally Posted by KILLER-LS1
im not sure what you mean by "shut down"
The ABS and TCS lights illuminate and the system stops operating.



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